Researcher Profile and Settings

Master

Affiliation (Master)

• Faculty of Science　Chemistry　Organic and Biological Chemistry

Affiliation (Master)

• Faculty of Science　Chemistry　Organic and Biological Chemistry

researchmap

Profile and Settings

Degree

• Kyoto University, Doctor of Engineering（Kyoto University）

Profile and Settings

• Name (Japanese)

  Sawamura

• Name (Kana)

  Masaya

• Name

  200901098220100993

Alternate Names

http://barato.sci.hokudai.ac.jp/~orgmet/

Achievement

Research Interests

• 有機金属化学   Organometallic Chemistry   

Research Areas

• Nanotechnology/Materials / Synthetic organic chemistry
• Life sciences / Bioorganic chemistry
• Nanotechnology/Materials / Structural/physical organic chemistry

Research Experience

• 2001 - Today - 北海道大学 教授
• 2001 - Today - Hokkaido University Professor
• 2019 - 2023 Hokkaido University Institute for Chemical Reaction Design and Discovery (WPI-ICReDD Professor
• 2016/04 - 2022/03 Hokkaido University Distinguished Professor
• 1997 - 2001 The University of Tokyo
• 1997 - 2001 The University of Tokyo, Associate Professor
• 1996 - 1997 The University of Tokyo
• 1996 - 1997 The University of Tokyo, Lecturer
• 1995 - 1996 The University of Tokyo
• 1995 - 1996 The University of Tokyo, Research Assistant
• 1995 - 1995 - 東京工業大学 助手
• 1995 - 1995 - Tokyo Institute of Technology, Research Assistant
• 1989 - 1995 京都大学 助手
• 1989 - 1995 Kyoto University, Research Assistant

Education

•        - 1989  Kyoto University
•        - 1989  Kyoto University  Graduate School, Division of Engineering
•        - 1984  Kyoto University  Faculty of Engineering
•        - 1984  Kyoto University  Faculty of Engineering

Awards

• 2022/05 日本産業衛生学会 第１３回GP奨励賞
   多数の作業場を抱える組織における効果的な職場巡視のための連携体制づくり〜大学の事例を通して〜 

  受賞者: 川上貴教、平井克美、澤村正也
• 2021/04 Ministry of Education, Culture, Sports, Science and Technology The Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology-Awards for Science and Technology-Research Category
   遷移金属有機合成触媒の設計と不斉制御の研究 

  受賞者: Masaya Sawamura
• 2020/02 北海道大学 北海道大学教育研究総長賞
   

  受賞者: 澤村正也
• 2019/02 The Society of Synthetic Organic Chemistry, Japan Synthetic Organic Chemistry Award
   Development of Carbon-Carbon Bond Forming Asymmetric Copper-Catalyzed Reactions 

  受賞者: SAWAMURA Masaya
• 2018/03 根岸賞
   

  受賞者: 澤村 正也
• 2017/01 名古屋シルバーメダル
   

  受賞者: 澤村 正也
• 2015/02 有機合成化学協会 日産化学・有機合成新反応／手法賞
   

  受賞者: 澤村 正也
• 2014/03 北海道大学研究総長賞
   

  受賞者: 澤村 正也
• 2012/03 日本化学会学術賞
   

  受賞者: 澤村 正也
• 1996/03 日本化学会進歩賞
  
• 1989/02 有機合成化学協会 「研究企画賞」
  

Published Papers

• Roles of Divinylbenzene Co‐Cross‐Linker in  a Threefold Cross‐Linked Polystyrene‐Phosphine Hybrid Monolith: Impact of Cross‐Linking Degree on Catalytic Performance

  Hikaru Matsumoto, Yu Hoshino, Tomohiro Iwai, Masaya Sawamura, Yoshiko Miura

  European Journal of Organic Chemistry 1434-193X 2024/09/26 

  Continuous‐flow organic transformations using immobilized catalysts are crucial for green and sustainable chemistry. Cross‐linked polymer ligands offer high stability, ease of recovery through filtration, and thus enhance performance in continuous‐flow reactions via transition‐metal catalysis. Additionally, the cross‐linking structure of the polymer support creates a unique reaction platform that controls the coordination behavior of the supported ligands and stabilizes the metal catalysts. However, insights into the material‐based design for preparing highly active and durable immobilized metal catalysts are still limited. In this report, we propose a straightforward approach to boost both selective mono‐coordination and effective stabilization of metal complexes. We developed threefold cross‐linked polystyrene‐triphenylphosphine hybrid monoliths with cross‐linking structures adjusted by varying the content of divinylbenzene as co‐cross‐linker. The coordination behaviors and metal‐support interactions of these monoliths were evaluated, highlighting the importance of co‐cross‐linker content in site‐isolating phosphine units and stabilizing metal centers via arene‐metal interactions on the polystyrene network. By optimizing the cross‐linking structure, the monolith catalysts demonstrated exceptionally high catalytic activity and durability in Pd‐catalyzed C‐Cl transformations, such as Suzuki‐Miyaura cross‐couplings and Buchwald‐Hartwig aminations in continuous flow. This underscores the utility of our monolith system in challenging transition‐metal catalysis.
• Boron-Catalyzed Michael Reaction of Donor–Acceptor Carboxylic Acid Pairs Enabling Direct Synthesis of 1,5-Dicarboxylic Acids

  Yukiho Yoshida, Masaya Sawamura, Yohei Shimizu

  Organic Letters 26 (26) 5425 - 5429 1523-7060 2024/06/19
• Gold‐Zinc Co‐Catalyzed Alkynoate Hydrocarboxylation with N‐Protected Amino Acids for Preparation of Storable Acylating Reagents and Racemization‐Free Peptide Synthesis

  Ayaka Sakurada, Miyu Sato, Kosuke Higashida, Masaya Sawamura

  Advanced Synthesis & Catalysis 1615-4150 2024/05/15 

  Abstract Hydrocarboxylation of methyl 2‐octynoate, a chemical commercially available at a low cost, with N‐protected amino acids was developed with a gold‐zinc cooperative catalyst constructed with a 5‐[(2,2′‐bipyridin)‐5‐yl]imidazo[1,5‐a]pyridin‐3‐ylidene to prepare α‐methoxycarbonyl enol esters as acylating reagents. The α‐methoxycarbonyl enol esters were isolable through silica‐gel column chromatography and storable without precautions regarding moisture. Acylation of free amines with the α‐methoxycarbonyl enol esters proceeded without epimerization of the stereogenic center derived from the enol esters, affording analytically pure dipeptide compounds through filtration and hexane‐washing.
• Continuous‐Flow Catalysis Using Phosphine‐Metal Complexes on Porous Polymers: Designing Ligands, Pores, and Reactors

  Hikaru Matsumoto, Tomohiro Iwai, Masaya Sawamura, Yoshiko Miura

  ChemPlusChem 2192-6506 2024/03/28 

  Continuous‐flow syntheses using immobilized catalysts can offer efficient chemical processes with easy separation and purification. In particular, porous polymers have gained significant interests for their applications to catalytic systems in the field of organic chemistry. The porous polymers are recognized for their large surface area, high chemical stability, facile modulation of surface chemistry, and cost‐effectiveness. It is crucial to immobilize transition‐metal catalysts due to their difficult separation and high toxicity. Supported phosphine ligands represent a noteworthy system for the effective immobilization of metal catalysts and modulation of catalytic properties. Researchers have been actively pursuing strategies involving phosphine‐metal complexes supported on porous polymers, aiming for high activities, durabilities, selectivities, and applicability to continuous‐flow systems. This review provides a concise overview of phosphine‐metal complexes supported on porous polymers for continuous‐flow catalytic reactions. Polymer catalysts are categorized based on pore sizes, including micro‐, meso‐, and macroporous polymers. The characteristics of these porous polymers are explored concerning their efficiency in immobilized catalysis and continuous‐flow systems.
• 20.2.1.8.15 Synthesis of Carboxylic Acids with Retention of the Functional Group (Update 2024)

  M. Sawamura, Y. Shimizu

  Knowledge Updates 2024/2 2024 

  Abstract Carboxylic acids are readily available feedstock materials, and are also found in natural products, pharmaceuticals, agrochemicals, and other biologically active compounds. Hence, efficient methods to transform carboxylic acids into other value-added compounds is of great importance. This review is an update to Science of Synthesis Section 20.2.1.8 on the synthesis of carboxylic acids with “retention of the functional group”. The main focus of this review is placed on asymmetric reactions and catalytic reactions, along with practical stoichiometric reactions, reported in the period 2010–2022. The transformations discussed include α-functionalizations, conjugate additions, and C(sp2)—H as well as C(sp3)—H functionalizations.
• The Aldol Reaction: Group III Enolates

  Masaya Sawamura, Yohei Shimizu

  Reference Module in Chemistry, Molecular Sciences and Chemical Engineering 2024
• Sheltering Mono-P-Ligated Metal Complexes in Porous Polystyrene Monolith: Effect of Aryl Pendant Stabilizers on Catalytic Durability.

  Hikaru Matsumoto, Yu Hoshino, Tomohiro Iwai, Masaya Sawamura, Yoshiko Miura

  Chemistry (Weinheim an der Bergstrasse, Germany) 29 (55) e202301847  2023/10/02 

  Metal centers that can generate coordinatively unsaturated metals in accessible and stable states have been developed using synthetic polymers with sophisticated ligand and scaffold designs, which required synthetic efforts. Herein, we report a simple and direct strategy for producing polymer-supported phosphine-metal complexes, which stabilizes mono-P-ligated metals by modulating the electronic properties of the aryl pendant groups in the polymer platform. A three-fold vinylated PPh3 was copolymerized with a styrene derivative and a cross-linker to produce a porous polystyrene-phosphine hybrid monolith. Based on the Hammett substituent constants, the electronic properties of styrene derivatives were modulated and incorporated into the polystyrene backbone to stabilize the mono-P-ligated Pd complex via Pd-arene interactions. Through NMR, TEM, and comparative catalytic studies, the polystyrene-phosphine hybrid, which induces selective mono-P-ligation and moderate Pd-arene interactions, demonstrated high catalytic durability for the cross-coupling of chloroarenes under continuous-flow conditions.
• Photocatalytic 1,2-Phosphorus-Migrative [3 + 2] Cycloaddition of Tri(t-butyl)phosphine with Terminal Alkynes

  Yusuke Masuda, Daichi Ikeshita, Kosuke Higashida, Masaki Yoshida, Naoki Ishida, Masahiro Murakami, Masaya Sawamura

  Journal of the American Chemical Society 0002-7863 2023/08/21
• Dimetal‐Binding Scaffold 2‐(Pyridin‐2‐yl)imidazo [1,5‐b]pyridazine‐7‐ylidene: Synthesis of Trinuclear Heterobimetallic Complexes Involving Gold‐Metal Interactions

  Akito Kitabayashi, Yuriko Ono, Tetsuya Taketsugu, Masaya Sawamura, Kosuke Higashida

  Chemistry – A European Journal 0947-6539 2023/08/09 

  Abstract As a dimetal‐binding rigid scaffold, 2‐(pyridin‐2‐yl)imidazo[1,5‐b]pyridazine‐7‐ylidene was introduced. The scaffold was first converted into a meridional Au,N,N‐tridentate ligand through binding of a Au(I)Cl moiety at the carbene center. The Au(I) center and the N,N‐chelating moiety were expected to function as metallophilic and 4e‐σ‐donative interaction sites, respectively, in the binding of the second metal center. In this manner, various trinuclear heterobimetallic complexes were synthesized with different 3d‐metal sources, such as cationic Cu^I, Cu^II, Ni^II, and Co^II salts. SC‐XRD analysis showed that the mono‐3d‐metal di‐gold(I) trinuclear heterobimetallic complexes were constructed through gold(I)‐metal interactions. Metallophilic interactions were also investigated by quantum chemical calculations including the AIM and IGMH methods.
• Gold‐Zinc Cooperative Catalysis for Seven‐exo‐dig Hydrocarboxylation of Internal Alkynes

  Miyu Sato, Vishal Kumar Rawat, Kosuke Higashida, Masaya Sawamura

  Chemistry – A European Journal 0947-6539 2023/07/20
• Visible-Light-Induced Aminochlorination of Alkenes

  Emna Mejri, Kosuke Higashida, Yuta Kondo, Anna Nawachi, Hiroyuki Morimoto, Takashi Ohshima, Masaya Sawamura, Yohei Shimizu

  Organic Letters 1523-7060 2023/06/08
• Direct α-Trifluoromethylthiolation of Carboxylic Acids Enabled by Boron Catalysis

  Kai Sun, Chung-Yang Dennis Huang, Masaya Sawamura, Yohei Shimizu

  Synlett 0936-5214 2023/04/11 [Refereed][Invited]
   

  A boron-catalyzed direct α-trifluoromethylthiolation of carboxylic acids was developed. Catalytically generated boron enediolates reacts with electrophilic SCF3 reagent, N-SCF3-phthalimide, to provide α-SCF3 carboxylic acids without the need of substrate pre-activation. The method is applicable to direct modification of bioactive carboxylic acids. Data science analyses provided suitable models for substrate classification as well as yield prediction.
• Sequence-selective three-component reactions of alkyltrifluoroborates with α,β-unsaturated carbonyl compounds and vinylphosphonium salts

  Masaki Yoshida, Masaya Sawamura, Yusuke Masuda

  Organic Chemistry Frontiers 10 (14) 3654 - 3661 2023 

  A photocatalytic three-component reaction of alkyltrifluoroborates with two electron-deficient alkenes proceeds in a sequence-selective manner, which can be followed by Wittig olefination to afford γ,δ-unsaturated ketones and esters.
• Boron Catalysis in the Transformation of Carboxylic Acids and Carboxylic Acid Derivatives

  Masaya Sawamura, Yohei Shimizu

  European Journal of Organic Chemistry 1434-193X 2022/12/15 [Refereed][Invited]
  
• Nickel-Catalyzed Defluorophosphonylation of Aryl Fluorides

  Zhensheng You, Yusuke Masuda, Tomohiro Iwai, Kosuke Higashida, Masaya Sawamura

  The Journal of Organic Chemistry 87 (21) 14731 - 14737 0022-3263 2022/10/18 [Refereed]
  
• Photoinduced Alcoholic α‐C−H Bond Anti‐Markovnikov Addition to Vinylphosphonium Bromides Followed by Wittig Olefination: Two‐Step Protocol for α‐C−H Allylic Alkylation of Alcohols

  Masaki Yoshida, Masaya Sawamura, Yusuke Masuda

  ChemCatChem 2022/09/20 [Refereed][Invited]
  
• Silver‐Catalyzed Asymmetric Aldol Reaction of Isocyanoacetic Acid Derivatives Enabled by Cooperative Participation of Classical and Nonclassical Hydrogen Bonds

  Satoshi Sakai, Akane Fujioka, Koji Imai, Kei Uchiyama, Yohei Shimizu, Kosuke Higashida, Masaya Sawamura

  Advanced Synthesis & Catalysis 364 (14) 2333 - 2339 1615-4150 2022/07/19 [Refereed]
  
• Construction of Heterobimetallic Catalytic Scaffold with a Carbene-Bipyridine Ligand: Gold–Zinc Two-Metal Catalysis for Intermolecular Addition of O-Nucleophiles to Nonactivated Alkynes

  Vishal Kumar Rawat, Kosuke Higashida, Masaya Sawamura

  ACS Catalysis 12 (14) 8325 - 8330 2155-5435 2022/07/15 [Refereed]
  
• Insights into the Mechanism of Enantioselective Copper‐Catalyzed Ring‐Opening Allylic Alkylation of Cyclopropanols

  Akito Kitabayashi, Sho Mizushima, Kosuke Higashida, Yuto Yasuda, Yohei Shimizu, Masaya Sawamura

  Advanced Synthesis & Catalysis 364 (11) 1855 - 1862 1615-4150 2022/06/07 [Refereed]
  
• Photoinduced Copper-Catalyzed Asymmetric Acylation of Allylic Phosphates with Acylsilanes

  Yusuke Ueda, Yusuke Masuda, Tomohiro Iwai, Keisuke Imaeda, Hiroki Takeuchi, Kosei Ueno, Min Gao, Jun-ya Hasegawa, Masaya Sawamura

  Journal of the American Chemical Society 144 (5) 2218 - 2224 0002-7863 2022/01/06 [Refereed][Not invited]
  
• Visible Light-Induced Reductive Allylation of Aldehydes by Umpolung Approach

  Ibuki Tanaka, Masaya Sawamura, Yohei Shimizu

  Organic Letters 24 (2) 520 - 524 1523-7060 2021/12 [Refereed][Not invited]
  
• Synthesis of C,N,N-Cyclometalated Gold(III) Complexes with Anionic Amide Ligands

  Ryotaro Niizeki, Kosuke Higashida, Emna Mejri, Masaya Sawamura, Yohei Shimizu

  Synlett 33 (3) 282 - 292 0936-5214 2021/10/19 [Refereed]
   

  A series of neutral C,N,N Au(III) complexes was synthesized with N-(8-quinolinyl)benzamide derivatives and chiral N-(2-(oxazolin-2-yl)phenyl)benzamide derivatives. This convenient synthesis method for amide ligands as well as an operationally simple complexation by direct C-H auration permitted changes to both the steric and electronic properties of the Au(III) complexes for promoting catalytic three-component coupling of an aldehyde, an amine, and an alkyne.
• Access to Indole-Fused Benzannulated Medium-Sized Rings through a Gold(I)-Catalyzed Cascade Cyclization of Azido-Alkynes

  Luca C. Greiner, Shinsuke Inuki, Norihito Arichi, Shinya Oishi, Rikito Suzuki, Tomohiro Iwai, Masaya Sawamura, A. Stephen K. Hashmi, Hiroaki Ohno

  Chemistry - A European Journal 27 (51) 12992 - 12997 1521-3765 2021/09/09 

  Because benzannulated and indole-fused medium-sized rings are found in many bioactive compounds, combining these fragments might lead to unexplored areas of biologically relevant and uncovered chemical space. Herein is shown that α-imino gold carbene chemistry can play an important role in solving the difficulty in the formation of medium-sized rings. Namely, phenylene-tethered azido-alkynes undergo arylative cyclization through the formation of a gold carbene intermediate to afford benzannulated indole-fused medium-sized tetracycles. The reactions allow a range of different aryl substitution patterns and efficient access to these otherwise difficult-to-obtain medium-sized rings. This study also demonstrates the feasibility of the semihollow-shaped C-dtbm ligand for the construction of a nine-membered ring.
• Front Cover: Access to Indole‐Fused Benzannulated Medium‐Sized Rings through a Gold(I)‐Catalyzed Cascade Cyclization of Azido‐Alkynes (Chem. Eur. J. 51/2021)

  Luca C. Greiner, Shinsuke Inuki, Norihito Arichi, Shinya Oishi, Rikito Suzuki, Tomohiro Iwai, Masaya Sawamura, A. Stephen K. Hashmi, Hiroaki Ohno

  Chemistry – A European Journal 27 (51) 12917 - 12917 2021/09/09
• Access to Indole‐Fused Benzannulated Medium‐Sized Rings through a Gold(I)‐Catalyzed Cascade Cyclization of Azido‐Alkynes

  Luca C. Greiner, Shinsuke Inuki, Norihito Arichi, Shinya Oishi, Rikito Suzuki, Tomohiro Iwai, Masaya Sawamura, A. Stephen K. Hashmi, Hiroaki Ohno

  Chemistry – A European Journal 27 (51) 12992 - 12997 0947-6539 2021/09/09 [Refereed][Invited]
   

  Because benzannulated and indole-fused medium-sized rings are found in many bioactive compounds, combining these fragments might lead to unexplored areas of biologically relevant and uncovered chemical space. Herein is shown that α-imino gold carbene chemistry can play an important role in solving the difficulty in the formation of medium-sized rings. Namely, phenylene-tethered azido-alkynes undergo arylative cyclization through the formation of a gold carbene intermediate to afford benzannulated indole-fused medium-sized tetracycles. The reactions allow a range of different aryl substitution patterns and efficient access to these otherwise difficult-to-obtain medium-sized rings. This study also demonstrates the feasibility of the semihollow-shaped C-dtbm ligand for the construction of a nine-membered ring.
• Visible-Light-Driven α-Allylation of Carboxylic Acids

  Kai Sun, Masato Ueno, Keisuke Imaeda, Kosei Ueno, Masaya Sawamura, Yohei Shimizu

  ACS Catalysis 11 (15) 9722 - 9728 2155-5435 2021/08/06 [Refereed][Not invited]
  
• Construction of Medium-Sized Rings by Gold Catalysis

  Ronald L. Reyes, Tomohiro Iwai, Masaya Sawamura

  Chemical Reviews 121 (14) 8926 - 8947 0009-2665 2021/07/28 [Refereed][Invited]
  
• A Hollow-shaped Caged Triarylphosphine: Synthesis, Characterization and Applications to Gold(I)-catalyzed 1,8-Enyne Cycloisomerization

  Tomohiro Iwai, Yuto Goto, Zhensheng You, Masaya Sawamura

  Chemistry Letters 50 (6) 1236 - 1239 0366-7022 2021/06/05 [Refereed][Not invited]
  
• Nickel-Catalyzed Homocoupling of Aryl Ethers with Magnesium Anthracene Reductant

  Kosuke Higashida, Masaya Sawamura, Vishal Kumar Rawat

  Synthesis 0039-7881 2021/05/17 [Refereed][Invited]
   

  Nickel-catalyzed reductive homocoupling of aryl ethers has been achieved with Mg(anthracene)(thf)3 as a readily available low-cost reductant. DFT calculations provided a rationale for the specific efficiency of the diorganomagnesium-type two-electron reducing agent. The calculations show that the dianionic anthracene-9,10-diyl ligand reduces the two aryl ether substrates, resulting in the homocoupling reaction through supply of electrons to the Ni-Mg bimetallic system to form organomagnesium nickel(0)-ate complexes, which cause two sequential C–O bond cleavage reactions. The calculations also showed cooperative actions of Lewis acidic magnesium atoms and electron-rich nickel atoms in the C–O cleavage reactions.
• An Introductory Overview of C–H Bond Activation/ Functionalization Chemistry with Focus on Catalytic C(sp3)–H Bond Borylation

  Ronald Reyes, Masaya Sawamura

  KIMIKA 32 (1) 70 - 109 0115-2130 2021/05/13 [Refereed][Invited]
   

  The direct and selective functionalization of C–H bonds provides novel disconnections and innovative strategies to streamline the synthesis of molecules with diverse complexities. However, despite the significant advances in the elaboration of techniques for C–H activation, the utilization of unactivated C(sp3)–H bonds remains challenging. In particular, asymmetric transformation of C(sp3)–H bonds is underdeveloped owing to the lack of catalytic systems that can competently discriminate among ubiquitous C–H bonds in organic molecules. This short review aims to outline the challenges and strategies for the catalytic functionalization of C(sp3)–H bonds giving a general and non-exhaustive explanatory approach. Current strategies on the basis of the substrates and reaction mechanisms are summarized in Section 1. Examples of enantioselective C–H bond transformations are then given in Section 2. Finally, in Section 3, an outline of current methodologies towards the direct borylation of C(sp3)–H bonds is described to showcase the importance of developing techniques for catalytic C–H bond chemistry. While we try to cover all excellent reports available in the literature on this topic, any omissions are unintentional, taking note of the most representative examples available.
• Use of Imidazo[1,5‐ a ]pyridin‐3‐ylidene as a Platform for Metal‐Imidazole Cooperative Catalysis: Silver‐Catalyzed Cyclization of Alkyne‐Tethered Carboxylic Acids

  Vishal Kumar Rawat, Kosuke Higashida, Masaya Sawamura

  Advanced Synthesis & Catalysis 363 (6) 1631 - 1637 1615-4150 2021/03/16 [Refereed][Not invited]
  
• Phosphinylation of Non‐activated Aryl Fluorides through Nucleophilic Aromatic Substitution at the Boundary of Concerted and Stepwise Mechanisms

  Zhensheng You, Kosuke Higashida, Tomohiro Iwai, Masaya Sawamura

  Angewandte Chemie International Edition 60 (11) 5778 - 5782 1433-7851 2021/03/08 [Refereed][Not invited]
  
• Synthesis of 4‐Hydroxy‐2‐pyridinone Derivatives and Evaluation of Their Antioxidant/Anticancer Activities

  Wafaa S. Hamama, Eslam A. Ghaith, Mona E. Ibrahim, Masaya Sawamura, Hanafi H. Zoorob

  ChemistrySelect 6 (7) 1430 - 1439 2365-6549 2021/02/17 [Refereed][Not invited]
  
• Dumbbell‐Shaped 2,2’‐Bipyridines: Controlled Metal Monochelation and Application to Ni‐Catalyzed Cross‐Couplings

  Yongjoon Kim, Tomohiro Iwai, Sho Fujii, Kosei Ueno, Masaya Sawamura

  Chemistry – A European Journal 27 (7) 2289 - 2293 0947-6539 2021/02 [Refereed][Not invited]
   

  Dumbbell-shaped bipyridines, featuring distal steric effects of bipyridine C5- and C5'-triarylmethyl substituents, allowed controlled monochelation to transition metals. These newly synthesized ligands showed improved ligand performance compared to conventional bipyridine ligands in the Ni-catalyzed cross-electrophile coupling and the Ni/photoredox-synergistically catalyzed decarboxylative coupling. More information can be found in the Communication by T. Iwai, M. Sawamura, et al. (DOI: 10.1002/chem.202004053).
• Copper-Catalyzed Reactions of Alkylboranes

  Hirohisa Ohmiya, Masaya Sawamura

  Bulletin of the Chemical Society of Japan 94 (1) 197 - 203 0009-2673 2021/01/15 [Refereed][Invited]
  
• Asymmetric Remote C-H Borylation of Aliphatic Amides and Esters with a Modular Iridium Catalyst

  Reyes, Ronald L., Sato, Miyu, Iwai, Tomohiro, Suzuki, Kimichi, Maeda, Satoshi, Sawamura, Masaya

  Synthesis 2021
• Convenient Synthesis of Binary and Fused Pyrazole Ring Systems: Accredited by Molecular Modeling and Biological Evaluation

  Eslam A. Ghaith, Hanafi H. Zoorob, Mona E. Ibrahim, Masaya Sawamura, Wafaa S. Hamama

  ChemistrySelect 5 (47) 14917 - 14923 2365-6549 2020/12/18 [Refereed][Not invited]
  
• The Scope of 3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one (DHA)

  Eslam A. Ghaith, Hanafi H. Zoorob, Mona E. Ibrahim, Masaya Sawamura, Wafaa S. Hamama

  Current Organic Chemistry 24 (13) 1459 - 1490 1385-2728 2020/10/01 [Refereed][Not invited]
   

  Boron additions, such as carboboration, silaboration, diboration, or hydroboration of alkynes, offer efficient strategies for the synthesis of alkenylborons, which are versatile synthetic intermediates. Most of the reported reactions occur in syn addition mode. Accordingly, anti-selective boron addition to alkynes is an important challenge in modern organic synthesis. This chapter describes successful examples of anti-selective boron additions.
• Boron-Catalyzed alpha-Amination of Carboxylic Acids

  Morisawa Takuto, Sawamura Masaya, Shimizu Yohei

  ORGANIC LETTERS 21 (18) 7466 - 7469 1523-7060 2019/09/20 [Refereed][Not invited]
  
• Iridium-Catalyzed Alkene-Selective Transfer Hydrogenation with 1,4-Dioxane as Hydrogen Donor

  Zhang Deliang, Iwai Tomohiro, Sawamura Masaya

  ORGANIC LETTERS 21 (15) 5867 - 5872 1523-7060 2019/08/02 [Refereed][Not invited]
   

  The iridium-catalyzed transfer hydrogenation of alkenes using 1,4-dioxane as a hydrogen donor is described. The use of 1,2-bis-(dicyclohexylphosphino)ethane (DCyPE), featuring bulky and highly electron-donating properties, led to high catalytic activity. A polystyrene-cross-linking bisphosphine PS-DPPBz produced a reusable heterogeneous catalyst. These homogeneous and heterogeneous protocols achieved chemoselective transfer hydrogenation of alkenes over other potentially reducible functional groups such as carbonyl, nitro, cyano, and imino groups in the same molecule.
• Nickel-Copper-Catalyzed Hydroacylation of Vinylarenes with Acyl Fluorides and Hydrosilanes

  Ueda Yusuke, Iwai Tomohiro, Sawamura Masaya

  CHEMISTRY-A EUROPEAN JOURNAL 25 (40) 9410 - 9414 0947-6539 2019/07/17 [Refereed][Not invited]
   

  The hydroacylation of vinylarenes with acyl fluorides and hydrosilanes was enabled by a synergistic bimetallic Ni/Cu-catalytic system, giving access to the corresponding branched ketone products. The reaction takes place under mild conditions at 25-80 degrees C and tolerates base-sensitive functional groups such as methoxycarbonyl and acetoxy groups.
• Heterogeneous Nickel-Catalyzed Cross-Coupling between Aryl Chlorides and Alkyllithiums Using a Polystyrene-Cross-Linking Bisphosphine Ligand

  Yamazaki Yuki, Arima Nozomi, Iwai Tomohiro, Sawamura Masaya

  ADVANCED SYNTHESIS & CATALYSIS 361 (10) 2250 - 2254 1615-4150 2019/05/14 [Refereed][Not invited]
   

  A polystyrene-cross-linking bisphosphine ligand PS-DPPBz was used for Ni-catalyzed cross-coupling with organolithiums. A bench-stable precatalyst [NiCl2(PS-DPPBz)] enabled efficient coupling reactions between aryl chlorides and alkyllithiums. The heterogeneous Ni system showed good reusability.
• Iridium-Catalyzed Asymmetric Borylation of Unactivated Methylene C(sp3)–H Bonds

  Ronald L. Reyes, Tomohiro Iwai, Satoshi Maeda, Masaya Sawamura

  Journal of the American Chemical Society 141 (17) 6817 - 6821 0002-7863 2019/05 [Refereed]
  
• Nickel-Catalyzed Decarboxylation of Aryl Carbamates for Converting Phenols into Aromatic Amines

  Akihiro Nishizawa, Tsuyoshi Takahira, Kosuke Yasui, Hayato Fujimoto, Tomohiro Iwai, Masaya Sawamura, Naoto Chatani, Mamoru Tobisu

  Journal of the American Chemical Society 141 (18) 7261 - 7265 0002-7863 2019/04 [Refereed][Not invited]
   

  © 2019 American Chemical Society. Herein, we describe a new catalytic approach to accessing aromatic amines from an abundant feedstock, namely phenols. The most reliable catalytic method for converting phenols to aromatic amines uses an activating group, such as a trifluoromethane sulfonyl group. However, this activating group is eliminated as a leaving group during the amination process, resulting in significant waste. Our nickel-catalyzed decarboxylation reaction of aryl carbamates forms aromatic amines with carbon dioxide as the only byproduct. As this amination proceeds in the absence of free amines, a range of functionalities, including a formyl group, are compatible. A bisphosphine ligand immobilized on a polystyrene support (PS-DPPBz) is key to the success of this reaction, generating a catalytic species that is significantly more active than simple nonsupported variants.
• Asymmetric Synthesis of alpha-Alkylidene-beta-Lactams through Copper Catalysis with a Prolinol-Phosphine Chiral Ligand

  Imai Koji, Takayama Yurie, Murayama Hiroaki, Ohmiya Hirohisa, Shimizu Yohei, Sawamura Masaya

  ORGANIC LETTERS 21 (6) 1717 - 1721 1523-7060 2019/03/15 [Refereed][Not invited]
  
• A Polystyrene-Cross-Linking Tricyclohexylphosphine: Synthesis, Characterization and Applications to Pd-Catalyzed Cross-Coupling Reactions of Aryl Chlorides

  Arashima Junya, Iwai Tomohiro, Sawamura Masaya

  CHEMISTRY-AN ASIAN JOURNAL 14 (3) 411 - 415 1861-4728 2019/02/01 [Refereed][Not invited]
  
• P,P,P ',P '-Tetraethynylated Bisphosphine and P-C-P Pincer Ligands with Bulky End Caps: Synthesis, Coordination Properties and Application to Platinum-catalyzed 1,8-Enyne Cycloisomerization

  Iwai Tomohiro, Shibaike Kazutaka, Sawamura Masaya

  CHEMISTRY LETTERS 47 (9) 1162 - 1164 0366-7022 2018/09 [Refereed][Not invited]
  
• Palladium-Catalyzed Asymmetric C(sp(3))-H Allylation of 2-Alkylpyridines

  Murakami Ryo, Sano Kentaro, Iwai Tomohiro, Taniguchi Tohru, Monde Kenji, Sawamura Masaya

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 57 (30) 9465 - 9469 1433-7851 2018/07/20 [Refereed][Not invited]
   

  The palladium-catalyzed asymmetric side-chain C(alpha)-allylation of 2-alkylpyridines, without using an external base, was developed. The high linear selectivities and enantioselectivities were achieved using new chiral diamidophosphite monodentate ligands. Given that the reaction conditions do not require an external base, this catalyst system enabled chemoselective C(alpha)-allylation of 2-alkylpyridines containing alpha-carbonyl C-H bonds, which are more acidic than alpha-pyridyl C-H bonds.
• Synthesis, Properties, and Catalytic Application of a Triptycene-Type Borate-Phosphine Ligand

  Konishi Shota, Iwai Tomohiro, Sawamura Masaya

  ORGANOMETALLICS 37 (12) 1876 - 1883 0276-7333 2018/06/25 [Refereed][Not invited]
   

  A borate-containing caged triarylphosphine L-X (X = Na or NBu4), featuring a 9-phospha-10-boratriptycene framework, was synthesized and characterized by NMR spectroscopy and X-ray diffraction analysis. The NMR coupling constant of the corresponding phosphine selenide indicated a higher electron-donating property of the borate-phosphine L compared to that of the 9-phospha-10-silatriptycene derivative (Ph-TRIP). The coordination property of L-X to [PdCl(eta(3)-allyl)](2) was dependent on the countercation, giving a neutral Pd complex [PdCl(eta(3)-allyl)(L-NBu4)] from L-NBu4 in CH2Cl2 or a zwitterionic Pd complex [Pd(eta(3)-allyl)(MeCN)(L)] from L-Na in MeCN/CH2Cl2. Utility of L-X as a ligand for metal catalysis was demonstrated in the Pd-catalyzed Suzuki-Miyaura cross-coupling of aryl chlorides.
• Copper-Catalyzed Enantioselective Coupling between Allyl-boronates and Phosphates Using a Phenol-Carbene Chiral Ligand: Asymmetric Synthesis of Chiral Branched 1,5-Dienes

  Yuto Yasuda, Hirohisa Ohmiya, Masaya Sawamura

  Synthesis (Germany) 50 (11) 2235 - 2246 1437-210X 2018/06/01 [Refereed][Not invited]
   

  Details of the Cu-catalyzed enantioselective allyl-allyl coupling reaction between allylboronates and (Z)-allylic phosphates using a new chiral N -heterocyclic carbene (NHC) ligand containing a phenolic hydroxy group are presented. The copper catalysis delivers enantio-enriched chiral 1,5-dienes with a tertiary stereogenic center. Compatibility with various functional groups and the use of earth-abundant and relatively low-toxicity copper as a metal are attractive features of this protocol. The utility of the chiral phenol-NHC ligand for enantioselective copper catalysis with organoboron compounds is demonstrated and enantiodiscrimination models are discussed.
• Synthesis of Cyclobutene-Fused Eight-Membered Carbocycles through Gold-Catalyzed Intramolecular Enyne [2+2] Cycloaddition

  Tomohiro Iwai, Masahiro Ueno, Hiori Okochi, Masaya Sawamura

  Advanced Synthesis and Catalysis 360 (4) 670 - 675 1615-4169 2018/02/15 [Refereed][Not invited]
   

  Cationic gold(I) complexes with hollow-shaped triethynylphosphine ligands efficiently catalyzed intramolecular [2+2] cycloaddition of 1,9-enynes to afford cyclobutene-fused eight-membered carbocycles that were difficult to synthesize by other catalytic systems. Various 1,9-enynes with carbon linkers with or without a fused ring underwent efficient [2+2] cycloaddition with 5 mol% of the Au catalyst bearing the triarylmethyl-end-capped triethynylphosphine in CH2Cl2 at rt in the presence of MS 4A as an additive. More challenging 1,9-enyne substrates with fully saturated acyclic carbon linkers underwent eight-membered ring formation at 60 °C in ClCH2CH2Cl in the absence of MS 4A, forming monocyclic 1,3-dienes as major products. (Figure presented.).
• Nickel-catalyzed amination of aryl fluorides with primary amines

  Tomoya Harada, Yusuke Ueda, Tomohiro Iwai, Masaya Sawamura

  Chemical Communications 54 (14) 1718 - 1721 1364-548X 2018 [Refereed][Not invited]
   

  The Ni-catalyzed cross-coupling reaction between aryl fluorides and primary amines was enabled by the 1,2-bis(dicyclohexylphosphino)benzene (DCYPBz) or 1,2-bis(dicyclohexylphosphino)ethane (DCYPE) ligands. Both N-alkyl- and N-aryl-substituted primary amines participated in the selective reaction to form secondary amines. This protocol would potentially be useful for late-stage diversification of fluorinated compounds with complex structures for the synthesis of functionally interesting aniline derivatives.
• Phosphine-Catalyzed Anti -Hydroboration of Internal Alkynes

  Nagao, K., Yamazaki, A., Ohmiya, H., Sawamura, M.

  Organic Letters 20 (7) 1861 - 1865 1523-7060 2018 [Refereed][Not invited]
  
• Enantiocontrol by assembled attractive interactions in copper-catalyzed asymmetric direct alkynylation of α-ketoesters with terminal alkynes: OH⋯O/sp3-CH⋯O two-point hydrogen bonding combined with dispersive attractions

  Martin C. Schwarzer, Akane Fujioka, Takaoki Ishii, Hirohisa Ohmiya, Seiji Mori, Masaya Sawamura

  Chemical Science 9 (14) 3484 - 3493 2041-6539 2018 [Refereed][Not invited]
   

  Copper-catalyzed asymmetric direct alkynylation of α-ketoesters with terminal alkynes with chiral prolinol-phosphine ligands, most preferably (αR,2S)-1-(2-dicyclohexylphosphinobenzyl)-α-neopentyl-2-pyrrolidinemethanol, afforded various enantioenriched chiral propargylic tertiary alcohols. Quantum-chemical calculations using the BP86 density functional including Grimme's empirical dispersion correction [DF-BP86-D3(BJ)-PCM(tBuOH)/TZVPP//DF-BP86-D3(BJ)/SVP] show the occurrence of OH⋯O/sp3-CH⋯O two-point hydrogen bonding between the chiral ligand and the carbonyl group of the ketoester in the stereo-determining transition states. Combined with the hydrogen-bonding interactions orienting the ketoester substrate, dispersive attractions between the chiral ligand (P-cyclohexyl groups) and the ketoester in the favored transition states, rather than steric repulsions in the disfavored transition state explain the enantioselectivity of the asymmetric copper catalysis.
• Copper-catalyzed enantioselective intramolecular alkylboron allylic alkylation

  Kentaro Hojoh, Yoshinori Shido, Hirohisa Ohmiya, Masaya Sawamura

  Chemistry Letters 47 (5) 632 - 635 1348-0715 2018 [Refereed][Not invited]
   

  A reductive CC-bond-forming cyclization of vinyl-terminated allyl chlorides via alkene hydroboration with 9-BBN-H followed by Cu-catalyzed asymmetric intramolecular allylic alkylation with a new chiral phosphoramidite ligand produced six-membered ring compounds with a tertiary or quaternary stereogenic center in the ring with high enantioselectivity.
• Nickel-catalyzed amination of aryl fluorides with primary amines

  Tomoya Harada, Yusuke Ueda, Tomohiro Iwai, Masaya Sawamura

  Chemical Communications 54 (14) 1718 - 1721 1364-548X 2018 [Refereed][Not invited]
   

  The Ni-catalyzed cross-coupling reaction between aryl fluorides and primary amines was enabled by the 1,2-bis(dicyclohexylphosphino)benzene (DCYPBz) or 1,2-bis(dicyclohexylphosphino)ethane (DCYPE) ligands. Both N-alkyl- and N-aryl-substituted primary amines participated in the selective reaction to form secondary amines. This protocol would potentially be useful for late-stage diversification of fluorinated compounds with complex structures for the synthesis of functionally interesting aniline derivatives.
• Phosphine-Catalyzed anti-Carboboration of Alkynoates with 9-BBN-Based 1,1-Diborylalkanes: Synthesis and Use of Multisubstituted γ-Borylallylboranes

  Yamazaki, A., Nagao, K., Iwai, T., Ohmiya, H., Sawamura, M.

  Angewandte Chemie - International Edition Wiley-Blackwell 57 (12) 3196 - 3199 1433-7851 2018 [Refereed][Not invited]
  
• Enantioselective Rh- or Ir-catalyzed Directed C(sp(3))-H Borylation with Phosphoramidite Chiral Ligands

  Ronald L. Reyes, Tomoya Harada, Tohru Taniguchi, Kenji Monde, Tomohiro Iwai, Masaya Sawamura

  CHEMISTRY LETTERS 46 (12) 1747 - 1750 0366-7022 2017/12 [Refereed][Not invited]
   

  Enantioselective heteroatom-directed C(sp(3))-H borylation reactions of 2-aminopyridines and 2-alkylpyridines with Rh-and Ir catalytic systems using commercially available chiral monophosphine ligands, respectively, were developed. This methodology provides an innovative example of a homogeneous catalytic system for C(sp(3))-H borylation, and allows the direct synthesis of optically active alkylboronates with a moderate level of enantioselectivity.
• Polystyrene-Cross-Linking Ortho-Substituted Triphenylphosphines: Synthesis, Coordination Properties, and Application to Pd-Catalyzed Cross-Coupling of Aryl Chlorides

  Tomohiro Iwai, Kiichi Asano, Tomoya Harada, Masaya Sawamura

  BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 90 (8) 943 - 949 0009-2673 2017/08 [Refereed][Not invited]
   

  Polystyrene-cross-linking triphenylphosphines having methyl groups as ortho substituents were synthesized. Coordination of the polymer-bound tri(o-tolyl) phosphine-type ligand toward a Pd(II) complex was investigated by 31PCP/MASNMR spectroscopies. Effects of the ortho-methyl-substituent were evaluated in the Pd-catalyzed cross-coupling of aryl chlorides.
• Exploring the full catalytic cycle of rhodium(I)BINAP-catalysed isomerisation of allylic amines: a graph theory approach for path optimisation

  Takayoshi Yoshimura, Satoshi Maeda, Tetsuya Taketsugu, Masaya Sawamura, Keiji Morokuma, Seiji Mori

  CHEMICAL SCIENCE 8 (6) 4475 - 4488 2041-6520 2017/06 [Refereed][Not invited]
   

  We explored the reaction mechanism of the cationic rhodium(I)-BINAP complex catalysed isomerisation of allylic amines using the artificial force induced reaction method with the global reaction route mapping strategy, which enabled us to search for various reaction paths without assumption of transition states. The entire reaction network was reproduced in the form of a graph, and reasonable paths were selected from the complicated network using Prim's algorithm. As a result, a new dissociative reaction mechanism was proposed. Our comprehensive reaction path search provided rationales for the E/Z and S/R selectivities of the stereoselective reaction.
• Asymmetric Synthesis of beta-Lactams through Copper-Catalyzed Alkyne-Nitrone Coupling with a Prolinol-Phosphine Chiral Ligand

  Yurie Takayama, Takaoki Ishii, Hirohisa Ohmiya, Tomohiro Iwai, Martin C. Schwarzer, Seiji Mori, Tohru Taniguchi, Kenji Monde, Masaya Sawamura

  CHEMISTRY-A EUROPEAN JOURNAL 23 (35) 8400 - 8404 0947-6539 2017/06 [Refereed][Not invited]
   

  Prolinol-phosphine chiral ligands enabled highly enantioselective copper-catalyzed intermolecular alkyne-nitrone coupling (Kinugasa reaction) to produce 1,3,4-trisubstituted chiral beta-lactams. A high level of enantiocontrol was achieved not only with aryl-or alkenylacetylenes but also with alkylacetylenes, which were important but unfavorable substrates in the previously reported protocols. Two-point hydrogen bonding between the chiral ligand and the nitrone oxyanion consisting of O-H center dot center dot center dot O and C(sp(3)) H center dot center dot center dot O hydrogen bonds is proposed.
• A Polystyrene-Cross-Linking Bisphosphine: Controlled Metal Monochelation and Ligand-Enabled First-Row Transition Metal Catalysis

  Tomohiro Iwai, Tomoya Harada, Hajime Shimada, Kiichi Asano, Masaya Sawamura

  ACS CATALYSIS 7 (3) 1681 - 1692 2155-5435 2017/03 [Refereed][Not invited]
   

  A polystyrene-cross-linking bisphosphine PSDPPBz was synthesized through radical emulsion copolymer-ization between 4-t-butylstyrene as a monomer and tetraviny-lated 1,2-bis(diphenylphosphino)benzene (DPPBz) as a 4-fold cross-linker. The location of the DPPBz bisphosphine moiety at the branching points of the cross-linked network organic polymer allowed controlled bisphosphine monochelation to transition metals under conditions where homogeneous ligands may form bischelated single metal complexes or multinuclear complexes. PS-DPPBz showed high ligand performance in first-row transition metal catalysis, enabling challenging molecular Alkyl transformations that were not possible through the screening of existing homogeneous ligands. In the Ni-catalyzed amination of aryl chlorides with N-alkyl-substituted primary amines, the substrate scope has been expanded to include 2,6-disubstituted aryl chlorides and N-tertiary-alkyl-substituted primary amines. PS-DPPBz was effective for the Ni-catalyzed C-H/C-O coupling between 1,3-azoles and monocyclic aryl pivalates, which showed poor reactivity in the reported homogeneous catalytic system based on 1,2-bis(dicyclohexylphosphino)ethane (DCYPE). The usefulness of the polymer-cross-linking strategy was also demonstrated in alkene hydroboration reactions catalyzed by Cu or Co.
• Synthesis of alpha-Quaternary Formimides and Aldehydes through Umpolung Asymmetric Copper Catalysis with Isocyanides

  Kentaro Hojoh, Hirohisa Ohmiya, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY American Chemical Society ({ACS}) 139 (6) 2184 - 2187 0002-7863 2017/02 [Refereed][Not invited]
   

  A highly regio- and enantioselective copper catalyzed three-component coupling of isocyanides, hydrosilanes, and gamma,gamma-disubstituted allylic phosphates/chlorides to afford chiral alpha-quaternary formimides was enabled by the combined use of our original chiral naphthol-carbene ligand as a functional Cu-supporting ligand and LiOtBu as a stoichiometric Lewis base for Si. The formimides were readily converted to alpha-quaternary aldehydes.
• Synthesis, Coordination Properties, and Catalytic Application of Triarylmethane-Monophosphines

  Tomohiro Iwai, Ryotaro Tanaka, Masaya Sawamura

  ORGANOMETALLICS 35 (23) 3959 - 3969 0276-7333 2016/12 [Refereed][Not invited]
   

  A new class of triarylmethane-based phosphines (L1-L4) and their Pd(II) and Rh(I) complexes were synthesized and subsequently characterized by NMR spectroscopy and X-ray diffraction analysis. The reactions of these phosphines with [PdCl(pi-allyl)](2) gave the square-planar Pd(II) complexes [PdCl(pi-allyl)(L)] (L = L1-L4). The treatment of [PdCl(pi-allyl)(L3)] and [PdCl(pi-allyl)(L4)], which have CF3-substituted triarylmethane and 9-arylfluorene moieties, respectively, with LiOtBu afforded P,C(sp(3))-chelated palladacycle complexes. Reversibility between a C(sp(3))-M covalent bond and a C(sp(3))-H center dot center dot center dot M interaction was experimentally demonstrated using [RhCl(nbd)](2) as a Rh(I) source. The triarylmethane-monophosphines L1-L4 were applied to the Pd-catalyzed 1,4-addition of arylboronic acids to enones.
• Copper-Catalyzed Enantioselective Allyl-Allyl Coupling between Allylic Boronates and Phosphates with a Phenol/N-Heterocyclic Carbene Chiral Ligand

  Yuto Yasuda, Hirohisa Ohmiya, Masaya Sawamura

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 55 (36) 10816 - 10820 1433-7851 2016/08 [Refereed][Not invited]
   

  Copper-catalyzed enantioselective allyl-allyl coupling between allylboronates and either Z-acyclic or cyclic allylic phosphates using a new chiral N-heterocyclic carbene ligand, bearing a phenolic hydroxy, is reported. This reaction occurs with exceptional S(N)2-type regioselectivities and high enantioselectivities to deliver chiral 1,5-diene derivatives with a tertiary stereogenic center at the allylic/homoallylic position.
• Site-Selective and Stereoselective C(sp(3))-H Borylation of Alkyl Side Chains of 1,3-Azoles with a Silica-Supported Monophosphine-Iridium Catalyst

  Ryo Murakami, Tomohiro Iwai, Masaya Sawamura

  SYNLETT 27 (8) 1187 - 1192 0936-5214 2016/05 [Refereed][Not invited]
   

  Site-selective and stereoselective C(sp(3))-H borylation of alkyl side chains of 1,3-azoles with bis(pinacolato) diboron was effectively catalyzed by a silica-supported monophosphine-iridium catalyst. The borylation occurred under relatively mild conditions (2 mol% Ir, 5090 degrees C), affording the corresponding primary and secondary alkylboronates. This system was applicable to a variety of 1,3-(benzo) azoles such as thiazoles, oxazoles, and imidazoles.
• Construction of Quaternary Stereogenic Carbon Centers through Copper-Catalyzed Enantioselective Allylic Alkylation of Azoles

  Hirohisa Ohmiya, Heng Zhang, Saori Shibata, Ayumi Harada, Masaya Sawamura

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 55 (15) 4777 - 4780 1433-7851 2016/04 [Refereed][Not invited]
   

  Copper-catalyzed enantioselective allylic alkylation of azoles with ,-disubstituted primary allylic phosphates was achieved using a new chiral N-heterocyclic carbene ligand bearing a naphtholic hydroxy group. This reaction occurred with excellent branch regioselectivity and high enantioselectivity, thus forming a controlled all-carbon quaternary stereogenic center at the position to the heteroaromatic ring.
• Phosphine-Catalyzed Vicinal Acylcyanation of Alkynoates

  Murayama, H., Nagao, K., Ohmiya, H., Sawamura, M.

  Organic Letters 18 (7) 1706 - 1709 1523-7060 2016 [Refereed][Not invited]
  
• Copper-catalyzed semihydrogenation of internal alkynes with molecular hydrogen

  Wakamatsu, T., Nagao, K., Ohmiya, H., Sawamura, M.

  Organometallics 35 (10) 1354 - 1357 0276-7333 2016 [Refereed][Not invited]
  
• Synthesis and structures of a chiral phosphine-phosphoric acid ligand and its rhodium(I) complexes

  Tomohiro Iwai, Yuki Akiyama, Kiyoshi Tsunoda, Masaya Sawamura

  TETRAHEDRON-ASYMMETRY 26 (21-22) 1245 - 1250 0957-4166 2015/12 [Refereed][Not invited]
   

  The synthesis and characterization of a novel chiral phosphine phosphoric acid ligand, (R)-3-diphenylphosphino-1,1'-binaphthyl-2,2'-diyl hydrogenphosphate (2) and its rhodium(I) complexes are described. The single-crystal X-ray diffraction analysis of 2 showed the intermolecular hydrogen-bonding network of the phosphoric acid moiety. The reactions of 2 with [RhCl(cod)](2) in the presence of KOtBu or with [Rh(acac)(CO)(2)] (acac = acetylacetonate) gave P,O-chelating rhodium(I) complexes [Rh(2-H+)(cod)] 3 or [Rh(2-H+)(CO)](2) 4, respectively. Their molecular structures were determined by single-crystal X-ray diffraction. (C) 2015 Elsevier Ltd. All rights reserved.
• Silica-Supported Triptycene-Type Phosphine. Synthesis, Characterization, and Application to Pd-Catalyzed Suzuki-Miyaura Cross-Coupling of Chloroarenes

  Tomohiro Iwai, Shota Konishi, Tatsuya Miyazaki, Soichiro Kawamorita, Natsumi Yokokawa, Hirohisa Ohmiya, Masaya Sawamura

  ACS CATALYSIS 5 (12) 7254 - 7264 2155-5435 2015/12 [Refereed][Not invited]
   

  A silica-supported triptycene-type phosphine, Silica-TRIP, comprising a 9-phospha-10-silatriptycene (TRIP) and silica gel as a P-coordination center and a solid support, respectively, was synthesized and structurally characterized by nitrogen absorption measurements and solid-state CP/MAS NMR spectroscopy. Silica-TRIP exhibited a mono-P-ligating feature toward a Pd(II) complex, resulting in selective formation of a 1/1 Pd-P species even with an excess amount of the ligand. As a result, Silica-TRIP enabled Pd-catalyzed Suzuki-Miyaura cross-coupling reactions of chloroarenes under mild conditions, regardless of the moderate electrondonating nature of the triarylphosphine-based ligand.
• Transition-Metal-Catalyzed Site-Selective C-H Functionalization of Quinolines beyond C2 Selectivity

  Tomohiro Iwai, Masaya Sawamura

  ACS CATALYSIS 5 (9) 5031 - 5040 2155-5435 2015/09 [Refereed][Not invited]
   

  Quinoline is an important scaffold in many natural products, biologically active compounds, and functional materials. The C-H functionalization of quinoline scaffolds by transition metal catalysis provides an efficient method for rapidly obtaining substituted quinolines. This review summarizes recently reported transition-metal-catalyzed site-selective C-H functionalization of quinolines, excluding C2 selective reactions. A review of direct functionalization of quinoline N-oxides at the C8 position also is provided.
• Anti-selective vicinal silaboration and diboration of alkynoates through phosphine organocatalysis

  Nagao, K., Ohmiya, H., Sawamura, M.

  Organic Letters 17 (5) 1304 - 1307 1523-7060 2015 [Refereed][Not invited]
  
• Copper(I)-catalyzed intramolecular hydroalkoxylation of unactivated alkenes

  Murayama, H., Nagao, K., Ohmiya, H., Sawamura, M.

  Organic Letters 17 (9) 2039 - 2041 1523-7060 2015 [Refereed][Not invited]
  
• Copper-Catalyzed γ-Selective and Stereospecific Allylic Cross-Coupling with Secondary Alkylboranes

  Yasuda, Y., Nagao, K., Shido, Y., Mori, S., Ohmiya, H., Sawamura, M.

  Chemistry - A European Journal 21 (27) 9666 - 9670 0947-6539 2015 [Refereed][Not invited]
  
• Copper-catalyzed enantioselective allylic cross-coupling with alkylboranes

  Hojoh, K., Shido, Y., Nagao, K., Mori, S., Ohmiya, H., Sawamura, M.

  Tetrahedron 71 (37) 6519 - 6533 0040-4020 2015 [Refereed][Not invited]
  
• Synthesis of 1,1-Diborylalkenes through a Brønsted Base Catalyzed Reaction between Terminal Alkynes and Bis(pinacolato)diboron

  Morinaga, A., Nagao, K., Ohmiya, H., Sawamura, M.

  Angewandte Chemie - International Edition 54 (52) 15859 - 15862 1433-7851 2015 [Refereed][Not invited]
  
• Copper-catalyzed stereoselective conjugate addition of alkylboranes to alkynoates

  Wakamatsu, T., Nagao, K., Ohmiya, H., Sawamura, M.

  Beilstein Journal of Organic Chemistry 11 2444 - 2450 1860-5397 2015 [Refereed][Not invited]
  
• Copper-Catalyzed Allylic Substitution and Conjugate Addition with Alkylboranes

  Hirohisa Ohmiya, Masaya Sawamura

  JOURNAL OF SYNTHETIC ORGANIC CHEMISTRY JAPAN 72 (11) 1207 - 1217 0037-9980 2014/11 [Refereed][Not invited]
   

  This account describes our studies on the use of alkylboranes for copper-catalyzed allylic substitution and conjugate addition reactions. The wide availability of alkylboranes via the established alkene hydroboration reaction is an attractive feature of these transformations. Various functional groups are tolerated in the substrates. Catalytic mechanisms involving the formation of alkylcopper(I) species from alkylboranes through B/Cu transmetalation are proposed.
• Transition-Metal Catalysis with Hollow-Shaped Triethynylphosphine Ligands

  Tomohiro Iwai, Masaya Sawamura

  BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 87 (11) 1147 - 1160 0009-2673 2014/11 [Refereed][Not invited]
   

  Triethynylphosphines with bulky end caps such as triarylsilyl and triarylmethyl groups at allcyne termini have a novel molecular shape presenting a large, deep metal-binding cavity. The hollow-shaped triethynylphosphines functioned as effective ligands in the rhodium-catalyzed hydrosilylation of ketones with triorganosilanes due to the preferential formation of a mono-P-ligated rhodium species. Furthermore, the phosphines displayed remarkable rate enhancement in the gold(I)-catalyzed alkyne cyclization constructing six- to eight-membered ring compounds. It is proposed that the cavity in the ligand forces a nucleophilic center of the acetylenic compounds close to the gold-bound alkyne, making ring-closing anti attack feasible.
• Copper-Catalyzed Enantioselective Allylic Alkylation of Terminal Alkyne Pronucleophiles

  Ayumi Harada, Yusuke Makida, Tatsunori Sato, Hirohisa Ohmiya, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 136 (39) 13932 - 13939 0002-7863 2014/10 [Refereed][Not invited]
   

  The copper-catalyzed enantioselective allylic alkylation of terminal alkynes with primary allylic phosphates was developed by the use of a new chiral N-heterocyclic carbene ligand bearing a phenolic hydroxy group at the ortho position of one of the two N-aryl groups. This reaction occurred with excellent gamma-branch regioselectivity and high enantioselectivity, forming a controlled stereogenic center at the allylic/propargylic position. Various terminal alkynes, including silyl, aliphatic, and aromatic alkynes, could be used directly without premetalation of the C(sp)-H bond. On the basis of the results of experiments using an isomeric secondary allylic phosphate, which gave a branched product through a alpha-selective substitution reaction with retention of configuration, a reaction pathway involving 1,3-allylic migration of Cu in a ([sigma + pi]-allyl)copper(III) species is proposed.
• High-Density Monolayers of Metal Complexes: Preparation and Catalysis

  Kenji Hara, Masaya Sawamura, Atsushi Fukuoka

  CHEMICAL RECORD 14 (5) 869 - 878 1527-8999 2014/10 [Refereed][Not invited]
   

  Catalysts are one of the key materials for realizing a sustainable society. However, we may encounter problematic cases where conventional catalyst systems cannot provide effective solutions. We thus believe that the establishment of novel methods of catalyst preparation is currently necessary. Utilization of high-density monolayers of molecular metal complexes is our strategy, and we expect that this methodology will enable facile and systematic screening of unique and efficient catalysts. This Personal Account describes our challenges to establish such an immature method in catalyst preparation as well as the related background and perspective. Preparation and catalysis by high-density monolayers of Rh complexes with N-heterocyclic carbene, structurally compact phosphine and diisocyanide ligands on gold surfaces are presented. The catalytic application of a high-density Pd-bisoxazoline complex prepared on a single-crystal silicon surface is also shown. Uniquely high catalyst turnover numbers and high chemoselectivities were observed with these catalyst systems.
• Stereoselective C-H Borylations of Cyclopropanes and Cyclobutanes with Silica-Supported Monophosphane-Ir Catalysts

  Ryo Murakami, Kiyoshi Tsunoda, Tomohiro Iwai, Masaya Sawamura

  CHEMISTRY-A EUROPEAN JOURNAL 20 (41) 13127 - 13131 0947-6539 2014/10 [Refereed][Not invited]
   

  Heteroatom-directed C-H borylation of cyclopropanes and cyclobutanes was achieved with silica-supported monophosphane-Ir catalysts. Borylation occurred at the C-H bonds located gamma to the directing N or O atoms with exceptional cis stereoselectivity relative to the directing groups. This protocol was applied to the borylation of a tertiary C H bond of a ring-fused cyclopropane.
• Construction of Quaternary Stereogenic Carbon Centers through Copper- Catalyzed Enantioselective Allylic Cross- Coupling with Alkylboranes**

  Kentaro Hojoh, Yoshinori Shido, Hirohisa Ohmiya, Masaya Sawamura

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 53 (19) 4954 - 4958 1433-7851 2014/05 [Refereed][Not invited]
   

  A combination of an in situ generated chiral Cu-I/DTBM-MeO-BIPHEP catalyst system and EtOK enabled the enantioselective S(N)2-type allylic cross-coupling between alkylborane reagents and ,-disubstituted primary allyl chlorides with enantiocontrol at a useful level. The reaction generates a stereogenic quaternary carbon center having three sp(3)-alkyl groups and a vinyl group. This protocol allowed the use of terminal alkenes as nucleophile precursors, thus representing a formal reductive allylic cross-coupling of terminal alkenes. A reaction pathway involving addition/elimination of a neutral alkylcopper(I) species with the allyl chloride substrate is proposed.
• Silica-supported Tripod Triarylphosphines: Application to Palladium-catalyzed Borylation of Chloroarenes

  Tomohiro Iwai, Tomoya Harada, Ryotaro Tanaka, Masaya Sawamura

  CHEMISTRY LETTERS 43 (5) 584 - 586 0366-7022 2014/05 [Refereed][Not invited]
   

  Silica-supported tripod triarylphosphines that have a Ph3P-type core tripodally immobilized on a silica surface enabled the Pd-catalyzed borylation of chloroarenes with bis(pinacolato)di-boron under mild conditions. The immobilization in tripod was crucial for the excellent performance of the Ph3P-based ligands.
• Silica-Supported Tripod Triarylphosphane: Application to Transition Metal-Catalyzed C(sp(3))-H Borylations

  Tomohiro Iwai, Ryo Murakami, Tomoya Harada, Soichiro Kawamorita, Masaya Sawamura

  ADVANCED SYNTHESIS & CATALYSIS 356 (7) 1563 - 1570 1615-4150 2014/05 [Refereed][Not invited]
   

  A silica-supported tripod triarylphosphane (Silica-3p-TPP), containing a triphenylphosphane-type core tripodally immobilized on the silica surface, allows rhodium- and iridium-catalyzed C(sp(3))H borylations of amide, urea and alkylpyridine derivatives. The (PCP)-P-31/MAS NMR studies for the coordination behavior of the tripod phosphane towards a rhodium complex indicate efficient site isolation of the each phosphane center, allowing independent mono-P-coordination to the metal center.
• Carbon-Boron and Carbon-Silicon Bond Formation

  Masaya Sawamura, Hajime Ito

  Copper-Catalyzed Asymmetric Synthesis 157 - 178 2014/03/31 [Refereed][Not invited]
  
• Site-Selective C-H Borylation of Quinolines at the C8 Position Catalyzed by a Silica-Supported Phosphane-Iridium System

  Shota Konishi, Soichiro Kawamorita, Tomohiro Iwai, Patrick G. Steel, Todd B. Marder, Masaya Sawamura

  CHEMISTRY-AN ASIAN JOURNAL 9 (2) 434 - 438 1861-4728 2014/02 [Refereed][Not invited]
   

  Site-selective CH borylation of quinoline derivatives at the C8 position has been achieved by using a heterogeneous Ir catalyst system based on a silica-supported cage-type monophosphane ligand SMAP. The efficient synthesis of a corticotropin-releasing factor(1) (CRF1) receptor antagonist based on a late-stage CH borylation strategy demonstrates the utility of the C8 borylation reaction.
• Tripod Immobilization of Triphenylphosphane on a Silica-Gel Surface to Enable Selective Mono-Ligation to Palladium: Application to Suzuki-Miyaura Cross-Coupling Reactions with Chloroarenes

  Tomohiro Iwai, Ryotaro Tanaka, Tomoya Harada, Masaya Sawamura

  CHEMISTRY-A EUROPEAN JOURNAL 20 (4) 1057 - 1065 0947-6539 2014/01 [Refereed][Not invited]
   

  A silica-supported triphenylphosphane (Silica-3p-TPP) with a Ph3P-type core, immobilized on a silica surface, was synthesized and characterized by nitrogen-absorption measurements and solid-state NMR spectroscopy. The tripodal immobilization constrains the mobility of the phosphane molecule and causes the lone pair on the phosphorus atom to face in the direction perpendicular to the support, resulting in the selective formation of a 1:1 metal-phosphane species that is free from unfavorable steric repulsions caused by the silica surface. Heterogeneous Pd catalysts created in this manner enabled room-temperature Suzuki-Miyaura cross-coupling reactions with unactivated chloroarenes, despite the moderate electronic and steric nature of the Ph3P-based ligands. These catalysts also showed potential in reactions with more challenging substrates under mild conditions. Tripodally immobilized and well-dispersed phosphanes on the silica surface were crucial for high catalytic activity.
• Friedel-Crafts functionalization of the cyclopentadienyl ligand in buckymetallocenes

  Yutaka Matsuo, Yoichiro Kuninobu, Shingo Ito, Masaya Sawamura, Eiichi Nakamura

  DALTON TRANSACTIONS 43 (20) 7407 - 7412 1477-9226 2014 [Refereed][Not invited]
   

  Acylated buckyferrocene and ruthenocene, Fe(eta(5)-C60Me5)(eta(5)-C5H4COR)(R = Me, Ph, and CH=CHPh) and Ru(eta(5)-C60Me5)(eta(5)-C5H4COR) (R = Me and Ph), were obtained by Friedel- Crafts acylation of the parent buckymetallocenes with the corresponding acid chlorides and aluminum chloride in carbon disulfide at ambient temperature. The electron withdrawing and sterically hindered nature of the acyl groups were revealed by X-ray crystallography, infrared spectroscopy and electrochemical measurements. The possibility of further derivatizing the acylated products was illustrated by the conversion of the acetyl buckyruthenocene into the corresponding hydroxy and acetoxy compounds Ru(eta(5)-C60Me5)(eta(5)-C5H4CH-(OH)Me) and Ru(eta(5)-C60Me5)(eta(5)-C5H4CH(OAc)Me).
• Phosphine-catalyzed anti-carboboration of alkynoates with alkyl-, alkenyl-, and arylboranes

  Nagao, K., Ohmiya, H., Sawamura, M.

  Journal of the American Chemical Society 136 (30) 10605 - 10608 0002-7863 2014 [Refereed][Not invited]
  
• Threefold Cross-Linked Polystyrene-Triphenylphosphane Hybrids: Mono-P-Ligating Behavior and Catalytic Applications for Aryl Chloride Cross-Coupling and C(sp(3))-H Borylation

  Tomohiro Iwai, Tomoya Harada, Kenji Hara, Masaya Sawamura

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 52 (47) 12322 - 12326 1433-7851 2013/11 [Refereed][Not invited]
  
• Synthesis of Trisubstituted Alkenylstannanes through Copper-Catalyzed Three-Component Coupling of Alkylboranes, Alkynoates, and Tributyltin Methoxide

  Takamichi Wakamatsu, Kazunori Nagao, Hirohisa Ohmiya, Masaya Sawamura

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 52 (44) 11620 - 11623 1433-7851 2013/10 [Refereed][Not invited]
  
• Cooperative Catalysis of Metal and O-H center dot center dot center dot O/sp(3)-C-H center dot center dot center dot O Two-Point Hydrogen Bonds in Alcoholic Solvents: Cu-Catalyzed Enantioselective Direct Alkynylation of Aldehydes with Terminal Alkynes

  Takaoki Ishii, Ryo Watanabe, Toshimitsu Moriya, Hirohisa Ohmiya, Seiji Mori, Masaya Sawamura

  CHEMISTRY-A EUROPEAN JOURNAL 19 (40) 13547 - 13553 0947-6539 2013/09 [Refereed][Not invited]
   

  Catalyst-substrate hydrogen bonds in artificial catalysts usually occur in aprotic solvents, but not in protic solvents, in contrast to enzymatic catalysis. We report a case in which ligand-substrate hydrogen-bonding interactions cooperate with a transition-metal center in alcoholic solvents for enantioselective catalysis. Copper(I) complexes with prolinol-based hydroxy amino phosphane chiral ligands catalytically promoted the direct alkynylation of aldehydes with terminal alkynes in alcoholic solvents to afford nonracemic secondary propargylic alcohols with high enantioselectivities. Quantum-mechanical calculations of enantiodiscriminating transition states show the occurrence of a nonclassical sp(3)-CHO hydrogen bond as a secondary interaction between the ligand and substrate, which results in highly directional catalyst-substrate two-point hydrogen bonding.
• Synthesis of a chiral N-heterocyclic carbene bearing a m-terphenyl-based phosphate moiety as an anionic N-substituent and its application to copper-catalyzed enantioselective boron conjugate additions

  Tomohiro Iwai, Yuki Akiyama, Masaya Sawamura

  TETRAHEDRON-ASYMMETRY 24 (12) 729 - 735 0957-4166 2013/06 [Refereed][Not invited]
   

  A chiral N-heterocyclic carbene (NHC) ligand 1a bearing a m-terphenyl-based phosphate moiety as an anionic N-substituent has been developed. A rhodium complex [Rh(1a)(cod)](2) was synthesized and its structure was characterized by NMR and ESI-MS spectroscopy. This ligand gave high enantioselectivities in copper-catalyzed enantioselective boron conjugate additions to an alpha,beta-unsaturated ester to give a chiral B-boryl ester. (C) 2013 Elsevier Ltd. All rights reserved.
• Use of a Semihollow-Shaped Triethynylphosphane Ligand for Efficient Formation of Six- and Seven-Membered Ring Ethers through Gold(I)-Catalyzed Cyclization of Hydroxy-Tethered Propargylic Esters

  Hideto Ito, Ayumi Harada, Hirohisa Ohmiya, Masaya Sawamura

  ADVANCED SYNTHESIS & CATALYSIS 355 (4) 647 - 652 1615-4150 2013/03 [Refereed][Not invited]
   

  The formation of six- and seven-membered ring ethers from hydroxy-tethered propargylic esters was efficiently catalyzed by a cationic gold(I) complex with a semihollow-shaped triethynylphosphane ligand. This gold catalysis showed a tolerance toward the reactions of primary, secondary, and tertiary alcohol substrates with various substitution patterns. A sterically congested 2,2,6,6-tetraalkyl-substituted tetrahydropyran derivative as well as 6,6- and 7,6-fused bicyclic diethers were obtained in useful yields. In addition, the gold catalysis was applicable to the reaction of a sulfonamide-tethered propargylic ester to give a piperidine derivative.
• Synthesis of Primary and Secondary Alkylboronates through Site-Selective C(sp(3))-H Activation with Silica-Supported Monophosphine-Ir Catalysts

  Soichiro Kawamorita, Ryo Murakami, Tomohiro Iwai, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 135 (8) 2947 - 2950 0002-7863 2013/02 [Refereed][Not invited]
   

  The site-selective activation and borylation of unactivated C(sp(3))-H bonds in 2-alkylpyridines to form primary and secondary alkylboronates was achieved using silica-supported monophosphine-Ir catalysts. This borylation occurs selectively at C-H bonds located gamma to the pyridine nitrogen atom. The site-selectivity of this reaction suggests that the C-H bond cleavage occurs with the assistance of a proximity effect due to N-to-Ir coordination.
• Construction of Eight-Membered Carbocycles through Gold Catalysis with Acetylene-Tethered Silyl Enol Ethers

  Tomohiro Iwai, Hiori Okochi, Hideto Ito, Masaya Sawamura

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 52 (15) 4239 - 4242 1433-7851 2013 [Refereed][Not invited]
  
• Copper-Catalyzed gamma-Selective and Stereospecific Direct Allylic Alkylation of Terminal Alkynes: Synthesis of Skipped Enynes

  Yusuke Makida, Yurie Takayama, Hirohisa Ohmiya, Masaya Sawamura

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 52 (20) 5350 - 5354 1433-7851 2013 [Refereed][Not invited]
  
• Conjugate Reduction of alpha,beta-Unsaturated Carbonyl and Carboxyl Compounds with Poly(methylhydrosiloxane) Catalyzed by a Silica-Supported Compact Phosphane-Copper Complex

  Soichiro Kawamorita, Kenji Yamazaki, Hirohisa Ohmiya, Tomohiro Iwai, Masaya Sawamura

  ADVANCED SYNTHESIS & CATALYSIS 354 (18) 3440 - 3444 1615-4150 2012/12 [Refereed][Not invited]
   

  A silica-supported, cage-type, compact phosphane (Silica-SMAP) was used for the copper-catalyzed conjugate reduction of a,beta-unsaturated carbonyl and carboxyl compounds with poly(methylhydrosiloxane) (PMHS). The heterogeneous catalyst system showed high activity and chemoselectivity, and was easily separable from the reaction mixture after the reaction. Furthermore, the catalyst was reusable without loss of its high catalytic activity or selectivity.
• Copper-Catalyzed Enantioselective Allylic Substitution with Alkylboranes

  Yoshinori Shido, Mika Yoshida, Masahito Tanabe, Hirohisa Ohmiya, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 134 (45) 18573 - 18576 0002-7863 2012/11 [Refereed][Not invited]
   

  The first catalytic enantioselective allylic substitution reaction with alkylboron compounds has been achieved. The reaction between alkyl-9-BBN reagents and primary allylic Chlorides proceeded With excellent gamma-selectivities and high enantioselectivities under catalysis. of a Cu(I)-DTBM-SEGPHOS system. The protocol produces terminal alkenes with an allylic stereogenic center branched With functionalized sp(3)-alkyl groups. The reaction with a gamma-silicon-substituted allyl chloride affords an efficient strategy for the enantioselective synthesis of functionalized alpha-stereogenic chiral allylsilanes.
• Enantioselective Conjugate Addition of Alkylboranes Catalyzed by a Copper-N-Heterocyclic Carbene Complex

  Masaya Sawamura, Hirohisa Ohmiya, Mika Yoshida

  SYNTHESIS-STUTTGART 44 (21) A115 - A117 0039-7881 2012/11 [Refereed][Not invited]
  
• Synthesis of Allenylsilanes through Copper-Catalyzed gamma-Selective Coupling between gamma-Silylated Propargylic Phosphates and Alkylboranes

  Umi Yokobori, Hirohisa Ohmiya, Masaya Sawamura

  ORGANOMETALLICS 31 (22) 7909 - 7913 0276-7333 2012/11 [Refereed][Not invited]
   

  Copper-catalyzed gamma-selective coupling between gamma-silylated propargylic phosphates and alkylboron compounds (alkly-9-BBN, prepared by hydroboration of alkenes with 9-BBN-H) Produced allenylsilanes with exceptional selectivity. The reaction tolerated various functional groups in both the alkylboranes and the propargylic Phosphates to afford functionalized allenylsilanes. The reaction of enantioenriched gamma-silylated propargylic: phosphates proceeded with excellent: 1,3-anti stereoselectivity to give axially. chiral allenylsilanes.
• Rh-Catalyzed Borylation of N-Adjacent C(sp(3))-H Bonds with a Silica-Supported Triarylphosphine Ligand

  Soichiro Kawamorita, Tatsuya Miyazaki, Tomohiro Iwai, Hirohisa Ohmiya, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 134 (31) 12924 - 12927 0002-7863 2012/08 [Refereed][Not invited]
   

  Direct C(sp(3))-H borylation of amides, ureas, and 2-aminopyridine derivatives at the position alpha to the N atom, which gives the corresponding alpha-aminoalkylboronates, has been achieved with a heterogeneous catalyst system consisting of [Rh(OMe)(cod)](2) and a silica-supported triarylphosphine ligand (Silica-TRIP) that features an immobilized triptycene-type cage structure with a bridgehead P atom. The reaction occurs not only at terminal C-H bonds but also at internal secondary C-H bonds under mild reaction conditions (25-100 degrees C, 0.1-0.5 mol % Rh).
• Enantioselective Conjugate Addition of Alkylboranes Catalyzed by a Copper-N-Heterocyclic Carbene Complex

  Mika Yoshida, Hirohisa Ohmiya, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 134 (29) 11896 - 11899 0002-7863 2012/07 [Refereed][Not invited]
   

  The first catalytic enantioselective conjugate addition of alkylboron compounds has been achieved. Reactions between alkylboranes and imidazol-2-yl alpha,beta-unsaturated ketones proceeded with high enantioselectivity under the influence of a Cu(I) catalyst system, prepared in situ from CuCl, a new chiral imidazolium salt as a precursor for the N-heterocyclic carbene ligand, and PhOK. Alkylboranes are widely obtained via alkene hydroboration. A variety of functional groups are tolerated in alkylboranes and alpha,beta-unsaturated ketones.
• Efficient Preparation of beta-Branched gamma,delta-Unsaturated Esters through Copper-Catalyzed Allylic Alkylation of Ketene Silyl Acetal

  Dong Li, Hirohisa Ohmiya, Masaya Sawamura

  SYNTHESIS-STUTTGART 44 (9) 1304 - 1307 0039-7881 2012/05 [Refereed][Not invited]
   

  Copper-catalyzed allylic alkylation of ketene silyl acetals proceeded with excellent gamma-E-selectivity. Efficient alpha-to-gamma chirality transfer with anti-selectivity occurred in the reaction of enantioenriched secondary allylic phosphates, affording enantioenriched beta-branched gamma,delta-unsaturated esters. The reaction was readily scalable and highly reliable in terms of product yield and stereoselectivities.
• Functional Group Tolerable Synthesis of Allylsilanes through Copper-Catalyzed gamma-Selective Allyl-Alkyl Coupling between Allylic Phosphates and Alkylboranes

  Kazunori Nagao, Hirohisa Ohmiya, Masaya Sawamura

  SYNTHESIS-STUTTGART 44 (10) 1535 - 1541 0039-7881 2012/05 [Refereed][Not invited]
   

  A copper-catalyzed gamma-selective allyl-alkyl coupling between gamma-silylated allylic phosphates and alkylboron compounds (alkyl-9-BBN, prepared by hydroboration of alkenes with 9-BBN-H) produced allylsilanes. The reaction tolerated various functional groups in both the alkylboranes and the allylic phosphates, and afforded functionalized allylsilanes.
• Reversible 1,3-anti/syn-Stereochemical Courses in Copper-Catalyzed gamma-Selective Allyl-Alkyl Coupling between Chiral Allylic Phosphates and Alkylboranes

  Kazunori Nagao, Umi Yokobori, Yusuke Makida, Hirohisa Ohmiya, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 134 (21) 8982 - 8987 0002-7863 2012/05 [Refereed][Not invited]
   

  The stereochemical courses of the copper-catalyzed allyl-alkyl coupling between enantioenriched chiral allylic phosphates and alkylboranes were switchable between 1,3-anti and 1,3-syn selectivities by the choice of solvents and achiral alkoxide bases with different steric demands. The reactions with gamma-silylated allylic phosphates allow efficient synthesis of enantioenriched chiral allylsilanes with tertiary or quaternary carbon stereogenic centers. Cyclic and acyclic bimodal participation of alkoxyborane species in an organocopper addition-elimination sequence is proposed to account for the phenomenon of the anti/syn-stereochemical reversal.
• Practical procedure for copper(I)-catalyzed allylic boryl substitution with stoichiometric alkoxide base

  Hajime Ito, Takanori Miya, Masaya Sawamura

  TETRAHEDRON 68 (17) 3423 - 3427 0040-4020 2012/04 [Refereed][Not invited]
   

  We have developed a useful procedure for borylation using catalytic CuCl/Xantphos and stoichiometric K(O-t-Bu): the highly versatile method is suitable for the synthesis of allylboronates including those with terminal and internal allylic systems, cyclic structures, and functional groups. Optically active allylboronates were synthesized from prochiral substrates with a chiral diphosphine ligand using this procedure. The reaction rate is generally higher than the original Cu(O-t-Bu)/ligand catalyst system, which we previously reported. (C) 2011 Elsevier Ltd. All rights reserved.
• Copper(I)-Catalyzed Allylic Substitution of Silyl Nucleophiles through Si?Si Bond Activation

  Hajime Ito, Yuko Horita, Masaya Sawamura

  ADVANCED SYNTHESIS & CATALYSIS 354 (5) 813 - 817 1615-4150 2012/03 [Refereed][Not invited]
   

  We report the first copper(I)-catalyzed reaction between a disilane and allylic carbonates to produce allylsilanes. The silyl nucleophilic substitution proceeded primarily in a SN2 fashion whereas SN2' products were also obtained through s-p-s isomerization of the copper(III) intermediate depending on the substrates steric bulk.
• Synthesis of Conjugated Allenes through Copper-Catalyzed gamma-Selective and Stereospecific Coupling between Propargylic Phosphates and Aryl- or Alkenylboronates

  Mingyu Yang, Natsumi Yokokawa, Hirohisa Ohmiya, Masaya Sawamura

  ORGANIC LETTERS 14 (3) 816 - 819 1523-7060 2012/02 [Refereed][Not invited]
   

  A Cu-catalyzed gamma-selective coupling reaction between propargylic phosphates and aryl- or alkenylboronates afforded aryl- or alkenyl-conjugated allenes. The reaction showed excellent functional group compatibility in both the propargylic substrates and the boronates. The reaction of an enantioenriched propargylic phosphate proceeded with excellent chirality transfer with 1,3-anti stereochemistry to give axially chiral aryl- and alkenylallenes.
• Regio- and Stereocontrolled Introduction of Secondary Alkyl Groups to Electron-Deficient Arenes through Copper-Catalyzed Allylic Alkylation

  Yusuke Makida, Hirohisa Ohmiya, Masaya Sawamura

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 51 (17) 4122 - 4127 1433-7851 2012 [Refereed][Not invited]
  
• Rh-Catalyzed Ortho-Selective C-H Borylatiob of N-Functionalized Arenes with Silica-Supported Bridgehead Monophosphine Ligands

  Soichiro Kawamorita, Tatsuya Miyazaki, Hirohisa Ohmiya, Tomohiro Iwai, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 133 (48) 19310 - 19313 0002-7863 2011/12 [Refereed][Not invited]
   

  Supported phosphine-Rh systems, prepared in situ from silica-supported bridgehead monophosphines and [Rh(OH)(cod)]2, have enabled ortho-selective C-H borylation for a range of arenes containing nitrogen-based directing groups. The regioselectivity was excellent with various N-directing groups, including saturated and unsaturated N-heterocycles, tert-aminoalkyl groups, and iminetype C-N double bonds. The reaction showed significant tolerance toward steric repulsion around the reacting C-H bond. This Rh catalysis complements the Jr-catalyzed orthoborylation, which is effective for arenes with oxygen-based directing groups.
• General Approach to Allenes through Copper-Catalyzed gamma-Selective and Stereospecific Coupling between Propargylic Phosphates and Alkylboranes

  Hirohisa Ohmiya, Umi Yokobori, Yusuke Makida, Masaya Sawamura

  ORGANIC LETTERS 13 (23) 6312 - 6315 1523-7060 2011/12 [Refereed][Not invited]
   

  Copper-catalyzed gamma-selective coupling between propargylic phosphates and alkylboron compounds (alkyl-9-BBN, prepared by hydroboration of alkenes with 9-BBN-H) affords multisubstituted allenes with various functional groups. The reaction of enantioenriched propargylic phosphates to give axially chiral allenes proceeds with excellent point-to-axial chirality transfer with 1,3-anti stereochemistry.
• Copper-catalyzed Conjugate Additions of Alkylboranes to Aryl alpha,beta-Unsaturated Ketones

  Hirohisa Ohmiya, Yoshinori Shido, Mika Yoshida, Masaya Sawamura

  CHEMISTRY LETTERS 40 (9) 928 - 930 0366-7022 2011/09 [Refereed][Not invited]
   

  Conjugate addition of alkylboron compounds (alkyl-9-BBN) to aryl alpha,beta-unsaturated ketones proceeded in the presence of a catalytic amount (10 mol %) of [(IPr)CuCl] and t-BuOK. The alkylboranes are available through alkene hydroboration, and thus the overall process represents a reductive conjugate addition of alkenes to enone derivatives. A variety of functional groups are tolerated in both the alkenes and the alpha,beta-unsaturated ketones.
• Mechanistic Insight into the Anomalous syn-Selectivity Observed during the Addition of Allenylboronates to Aromatic Aldehydes

  Yusuke Sasaki, Masaya Sawamura, Hajime Ito

  CHEMISTRY LETTERS 40 (9) 1044 - 1046 0366-7022 2011/09 [Refereed][Not invited]
   

  The reaction of enantioenriched allenylboronate 3a (98% ee) with benzaldehyde gave homopropargylic alcohol syn- and anti-4b with anomalous syn addition selectivity (anti:syn = 29:71) and high cc (98% and 97%, respectively). The stereochemical outcome in terms of the absolute configuration shows that this reaction proceeds through a cyclic transition state. Density functional theoretical (DFT) calculations were carried out to elucidate the mechanism of this anomalous syn-selectivity.
• Intramolecular hydroamination of alkynic sulfonamides catalyzed by a gold-triethynylphosphine complex: Construction of azepine frameworks by 7-exo-dig cyclization

  Hideto Ito, Tomoya Harada, Hirohisa Ohmiya, Masaya Sawamura

  BEILSTEIN JOURNAL OF ORGANIC CHEMISTRY 7 951 - 959 1860-5397 2011/07 [Refereed][Not invited]
   

  The gold-catalyzed, seven-membered ring forming, intramolecular hydroamination of alkynic sulfonamides has been investigated. The protocol, with a semihollow-shaped triethynylphosphine as a ligand for gold, allowed the synthesis of a variety of azepine derivatives, which are difficult to access by other methods. Both alkynic sulfoamides with a flexible linear chain and the benzene-fused substrates underwent 7-exo-dig cyclization to afford the nitrogen-containing heterocyclic seven-membered rings, such as tetrahydroazepine and dihydrobenzazepine, in good yields.
• Copper-Catalyzed gamma-Selective and Stereospecific Allylic Alkylation of Ketene Silyl Acetals

  Dong Li, Hirohisa Ohmiya, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 133 (15) 5672 - 5675 0002-7863 2011/04 [Refereed][Not invited]
   

  Copper-catalyzed allylic alkylation of ketene silyl acetals proceeded with excellent gamma-E-selectivity. Efficient alpha-to-gamma chirality transfer with anti-selectivity occurred in the reaction of enantioenriched secondary allylic phosphates, affording enantioenriched beta-branched gamma,delta-unsaturated esters. Excellent functional group compatibility was observed.
• Copper-Catalyzed Carboxylation of Alkylboranes with Carbon Dioxide: Formal Reductive Carboxylation of Terminal Alkenes

  Hirohisa Ohmiya, Masahito Tanabe, Masaya Sawamura

  ORGANIC LETTERS 13 (5) 1086 - 1088 1523-7060 2011/03 [Refereed][Not invited]
   

  Carboxylation of alkylboron compounds (alkyl-9-BBN) with CO2 proceeded in the presence of catalytic amounts of CuOAc/1,10-phenanthroline and a stoichiometric amount of (KOBu)-Bu-t. The alkylboranes are easily and widely available through the alkene hydroboration, and thus the overall process represents a reductive carboxylation of alkenes with CO2. The broad functional group compatibility and the inexpensiveness of the Cu/1,10-phenathoroline catalyst system are attractive features of this protocol.
• Sulfonamidoquinoline/Palladium(II)-Dimer Complex As a Catalyst Precursor for Palladium-Catalyzed gamma-Selective and Stereospecific Allyl-Aryl Coupling Reaction between Allylic Acetates and Arylboronic Acids

  Yusuke Makida, Hirohisa Ohmiya, Masaya Sawamura

  CHEMISTRY-AN ASIAN JOURNAL 6 (2) 410 - 414 1861-4728 2011/02 [Refereed][Not invited]
  
• Copper-Catalyzed Conjugate Additions of Alkylboranes to Imidazolyl alpha,beta-Unsaturated Ketones: Formal Reductive Conjugate Addition of Terminal Alkenes

  Hirohisa Ohmiya, Mika Yoshida, Masaya Sawamura

  ORGANIC LETTERS 13 (3) 482 - 485 1523-7060 2011/02 [Refereed][Not invited]
   

  Conjugate addition of alkylboron compounds (allryl-9-BBN) to imidazol-2-yl alpha,beta-unsaturated ketones proceeded in the presence of a catalytic amount (10 mol %) of CuCl, 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes), and t-BuOK. The alkylboranes are available through alkene hydroboration, and thus the overall process represents a reductive conjugate addition of alkenes to enone derivatives. A variety of functional groups are tolerated in both the alkenes and the alpha,beta-unsaturated ketones. The 2-acylimidazole moiety can easily be converted into the corresponding carboxylic acid, ester, and amide derivatives.
• Palladium-Catalyzed Borylation of Sterically Demanding Aryl Halides with a Silica-Supported Compact Phosphane Ligand

  Soichiro Kawamorita, Hirohisa Ohmiya, Tomohiro Iwai, Masaya Sawamura

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 50 (36) 8363 - 8366 1433-7851 2011 [Refereed][Not invited]
  
• Copper(I)-Catalyzed Regioselective Monoborylation of 1,3-Enynes with an Internal Triple Bond: Selective Synthesis of 1,3-Dienylboronates and 3-Alkynylboronates

  Sasaki Y, Horita Y, Zhong C. M, Sawamura M, Ito H

  Angewandte Chemie-International Edition 50 (12) 2778 - 2782 2011 [Refereed][Not invited]
  
• Direct enantio-convergent transformation of racemic substrates without racemization or symmetrization

  Hajime Ito, Shun Kunii, Masaya Sawamura

  NATURE CHEMISTRY 2 (11) 972 - 976 1755-4330 2010/11 [Refereed][Not invited]
   

  Asymmetric reactions that transform racemic mixtures into enantio-enriched products are in high demand, but classical kinetic resolution produces enantiopure compounds in <50% yield even in an ideal case. Many deracemization processes have thus been developed including dynamic kinetic resolution and dynamic kinetic asymmetric transformation, which can provide enantio-enriched products even after complete conversion of the racemic starting materials. However, these dynamic processes require racemization or symmetrization of the substrates or intermediates. We demonstrate a direct chemical enantio-convergent transformation without a racemization or symmetrization process. Copper(I)-catalysed asymmetric allylic substitution of a racemic allylic ether afforded a single enantiomer of an a-chiral allylboronate with complete conversion and high enantioselectivity (up to 98% enantiomeric excess). One enantiomer of the substrate undergoes an anti-S(N)2'-type reaction whereas the other enantiomer reacts via a syn-S(N)2' pathway. The products, which cannot be prepared by dynamic procedures, have been used to construct all-carbon quaternary stereocentres.
• Construction of Methylenecycloheptane Frameworks through 7-Exo-Dig Cyclization of Acetylenic Silyl Enol Ethers Catalyzed by Triethynylphosphine-Gold Complex

  Hideto Ito, Hirohisa Ohmiya, Masaya Sawamura

  ORGANIC LETTERS 12 (19) 4380 - 4383 1523-7060 2010/10 [Refereed][Not invited]
   

  A cationic gold(I) complex bearing a semihollow-shaped triethynylphosphine ligand efficiently catalyzed the 7-exo-dig cyclization of silyl enol ethers with an omega-alkynic substituent. The reaction gave various methylenecycloheptane derivatives with an exo- or endocyclic carbonyl group. The protocol was applicable not only to cyclic substrates that form bicyclic frameworks but also to acyclic ones with or without substituents in a carbon chain tether.
• Protecting-Group-Free Route to Hydroxylated Pyrrolidine and Piperidine Derivatives through Cu(I)-Catalyzed Intramolecular Hydroamination of Alkenes

  Hirohisa Ohmiya, Mika Yoshida, Masaya Sawamura

  SYNLETT (14) 2136 - 2140 0936-5214 2010/09 [Refereed][Not invited]
   

  An efficient approach to hydroxylated pyrrolidine and piperidine derivatives through the intramolecular hydroamination catalyzed by a Cu(I)-Xantphos system is described. The transformation allows for the short synthesis of N-alkylated aza-sugars without a protection-deprotection event of the hydroxy groups.
• Directed Ortho Borylation of Phenol Derivatives Catalyzed by a Silica-Supported Iridium Complex

  Kenji Yamazaki, Soichiro Kawamorita, Hirohisa Ohmiya, Masaya Sawamura

  ORGANIC LETTERS 12 (18) 3978 - 3981 1523-7060 2010/09 [Refereed][Not invited]
   

  The directed ortho borylation of phenol derivatives protected with an N,N-diethylcarbamoyl group was efficiently catalyzed by an immobilized monophosphine-Ir system, which was prepared in situ from [Ir(OMe)(cod)](2) and a silica-supported, compact phosphine. The utility of the carbamoyloxy group as a leaving group for metal-catalyzed cross-coupling reactions was demonstrated by its utilization in the synthesis of a terphenyl derivative.
• Enantioselective Synthesis of trans-Aryl- and -Heteroaryl-Substituted Cyclopropylboronates by Copper(I)-Catalyzed Reactions of Allylic Phosphates with a Diboron Derivative

  Chongmin Zhong, Shun Kunii, Yuki Kosaka, Masaya Sawamura, Hajime Ito

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 132 (33) 11440 - 11442 0002-7863 2010/08 [Refereed][Not invited]
   

  A new asymmetric route for the synthesis of trans-2-aryl- and -heteroaryl-substituted cyclopropylboronates has been developed. (Z)-3-arylallylic phosphates were converted to the optically active products with high yield and diastereo- and enantioselectivity through a copper(I)-catalyzed reaction with a diboron derivative. Under mild reaction conditions, the reaction affords the arylcyclopropane products with a functional group and a heteroaromatic group in a highly enantioselective manner. When (E)-allylic phosphates were used as substrates, a ligand-controlled product switch between the trans and cis configurations was observed.
• Synthesis of alpha-Arylated Allylsilanes through Palladium-Catalyzed gamma-Selective Allyl-Aryl Coupling

  Dong Li, Tatsunori Tanaka, Hirohisa Ohmiya, Masaya Sawamura

  ORGANIC LETTERS 12 (15) 3344 - 3347 1523-7060 2010/08 [Refereed][Not invited]
   

  A palladium-catalyzed gamma-selective allyl -aryl coupling between gamma-silylated allylic esters and arylboronic acids produced alpha-arylated allylsilanes with E-alkene geometry. The reaction tolerated various functional groups In both the arylboronic acids and the allylic esters and afforded functionalized allylsilanes. The reaction of optically active allylic esters took place with excellent alpha-to-gamma chirality transfer with syn stereochemistry to give chiral allylsilanes.
• Ester-Directed Regioselective Borylation of Heteroarenes Catalyzed by a Silica-Supported Iridium Complex

  Soichiro Kawamorita, Hirohisa Ohmiya, Masaya Sawamura

  JOURNAL OF ORGANIC CHEMISTRY 75 (11) 3855 - 3858 0022-3263 2010/06 [Refereed][Not invited]
   

  The ester-directed regioselective borylation of arenes catalyzed by a silica-supported monophosphine-Ir complex displayed a significantly broad substrate scope toward heteroaromatic compounds, including thiophene. pyrrole, furan, benzothiophene, benzofuran, indole, and carbazole derivatives. The regioselectivity is complementary to the selectivities observed in the heteroarene C-H borylation with the dtbpy-Ir catalyst system.
• Stereospecific Synthesis of Cyclobutylboronates through Copper(I)-Catalyzed Reaction of Homoallylic Sulfonates and a Diboron Derivative

  Hajime Ito, Takashi Toyoda, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 132 (17) 5990 - + 0002-7863 2010/05 [Refereed][Not invited]
   

  A copper(I)-catalyzed stereospecific reaction for the preparation of cis- and trans-1-silyl-2-borylcyclobutanes as well as 1-phenyl-2-borylcyclobutanes is reported. (Z)- and (E)-Homoallylic methanesulfonates were converted to the corresponding trans- and cis-cyclobutane derivatives, respectively, in the presence of a CuCl/dppp catalyst, bis(pinacolato)diboron, and K(O-t-Bu)/THF. Stereospecific derivatizations of the cis- and trans-borylcyclobutanes were carried out to demonstrate the utility of the borylcyclobutanes.
• Copper-Catalyzed gamma-Selective and Stereospecific Allyl-Aryl Coupling between (Z)-Acyclic and Cyclic Allylic Phosphates and Arylboronates

  Hirohisa Ohmiya, Natsumi Yokokawa, Masaya Sawamura

  ORGANIC LETTERS 12 (10) 2438 - 2440 1523-7060 2010/05 [Refereed][Not invited]
   

  A Cu-catalyzed allyl-aryl coupling reaction between (2)-acyclic or cyclic allylic phosphates and arylboronates proceeds with excellent gamma-E-selectivity and 1,3-anti chirality transfer, which gives the corresponding coupling products with benzylic and allylic stereogenic centers. The wide availability and easy-to-handle nature of arylboronates, the inexpensiveness of the Cu catalyst system, and the high regio- and stereoselectivities are attractive features of this protocol.
• Selective Synthesis of Allenes and Alkynes through Ligand-Controlled, Palladium-Catalyzed Decarboxylative Hydrogenolysis of Propargylic Formates

  Hirohisa Ohmiya, Mingyu Yang, Yoshihiro Yamauchi, Yuhki Ohtsuka, Masaya Sawamura

  ORGANIC LETTERS 12 (8) 1796 - 1799 1523-7060 2010/04 [Refereed][Not invited]
   

  Ligand-controlled regioselective palladium-catalyzed decarboxylative hydrogenolysis of propargylic formates is described. A wide range of allenes and alkynes were obtained by using either 1,2-diphenylphosphinoethane (DPPE) or 1,6-bisdiphenylphosphinohexane (DPPH) as a catalyst ligand.
• Copper-Catalyzed gamma-Selective Allyl-Alkyl Coupling between Allylic Phosphates and Alkylboranes

  Hirohisa Ohmiya, Umi Yokobori, Yusuke Makida, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 132 (9) 2895 - + 0002-7863 2010/03 [Refereed][Not invited]
   

  Copper-catalyzed allyl-alkyl coupling between allylic phosphates and alkylboranes, prepared by hydroboration of alkenes with 9-BBN-H, takes place with complete gamma- and E-selectivities and with preferential 1,3-anti stereochemistry. The reaction tolerates various functional groups in both the allylic phosphate and alkylborane. Catalytic mechanisms involving transmetalation between a trialkyl(alkoxo)borate and a copper(I) complex to form an alkylcopper(I) species are proposed.
• Catalysis with densely packed monolayer of metal-phosphine complex on gold surface

  Kenji Hara, Ryuto Akiyama, Kohei Uosaki, Atsushi Fukuoka, Masaya Sawamura

  ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 239 0065-7727 2010/03 [Refereed][Not invited]
  
• Copper(I)-Catalyzed Asymmetric Monoborylation of 1,3-Dienes: Synthesis of Enantioenriched Cyclic Homoallyl- and Allylboronates

  Yusuke Sasaki, Chongmin Zhong, Masaya Sawamura, Hajime Ito

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 132 (4) 1226 - + 0002-7863 2010/02 [Refereed][Not invited]
   

  Copper(I)-catalyzed asymmetric monoborylation of 1,3-dienes has been developed. We describe the production of either optically active homoallyl- or allylboronates with high regio- and enantioselectivity (88-97% ee) through monoborylation of 1,3-dienes. The reaction with 1,3-cyclohexadiene derivatives afforded the corresponding enantioenriched homoallyboronates. By simply changing the reaction conditions, a drastic change of product preference between homoallyl- and allylboronates was found in the reaction of 1,3-cyclopentadiene and 1,3-cycloheptadiene.
• Palladium-Catalyzed gamma-Selective and Stereospecific Allyl-Aryl Coupling between Acyclic Allylic Esters and Arylboronic Acids

  Hirohisa Ohmiya, Yusuke Makida, Dong Li, Masahito Tanabe, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 132 (2) 879 - 889 0002-7863 2010/01 [Refereed][Not invited]
   

  Reactions between acyclic (E)-allylic acetates and arylboronic acids in the presence of a palladium catalyst prepared from Pd(OAc)(2), phenanthroline (or bipyridine), and AgSbF(6) (1:1.2:1) proceeded with excellent gamma-selectivity to afford allyl-aryl coupling products with E-configuration. The reactions of a-chiral allylic acetates took place with excellent alpha-to-gamma chirality transfer with syn stereochemistry to give allylated arenes with a stereogenic center at the benzylic position. The reaction tolerated a broad range of functional groups in both the allylic acetates and the arylboronic acids. Furthermore, gamma-arylation of cinnamyl alcohol derivatives afforded gem-diarylalkane derivatives containing an unconjugated alkenic substituent. The synthetic utility of this method was demonstrated by its utilization in an efficient synthesis of (+)-sertraline, an antidepressant agent. The observed gamma-regioselectivity and E-1,3-syn stereochemistry were rationalized based on a Pd(II) mechanism involving transmetalation between a cationic mono(acyloxo)palladium(II) complex and arylboronic acid, and directed carbopalladation followed by syn-beta-acyloxy elimination. The results of stoichionnetric reactions of palladium complexes related to possible intermediates were fully consistent with the proposed mechanism.
• Desymmetrization of meso-2-Alkene-1,4-diol Derivatives through Copper(I)-Catalyzed Asymmetric Boryl Substitution and Stereoselective Allylation of Aldehydes

  Hajime Ito, Takuma Okura, Kou Matsuura, Masaya Sawamura

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 49 (3) 560 - 563 1433-7851 2010 [Refereed][Not invited]
  
• General and Functional Group-Tolerable Approach to Allenylsilanes by Rhodium-Catalyzed Coupling between Propargylic Carbonates and a Silylboronate

  Hirohisa Ohmiya, Hideto Ito, Masaya Sawamura

  ORGANIC LETTERS 11 (24) 5618 - 5620 1523-7060 2009/12 [Refereed][Not invited]
   

  The Rh-catalyzed coupling reaction between propargylic carbonates and a silylboronate afforded allenylsilanes with different substitution patterns in high yields. The reaction tolerates a variety of functional groups in propargylic carbonates. The reaction of an optically active propargylic carbonate proceeded with excellent chirality transfer with 1,3-anti stereochemistry to give an axially chiral allenylsilane.
• Air-Stable, Compact, Caged Trialkylphosphines (SMAPs): Synthesis, Properties and Applications to Homogeneous and Heterogeneous Catalysis

  Masaya Sawamura

  JOURNAL OF SYNTHETIC ORGANIC CHEMISRY, JAPAN The Society of Synthetic Organic Chemistry, Japan 67 (11) 1125 - 1135 0037-9980 2009/11 [Refereed][Invited]
   

  Synthesis, properties and applications to transition metal catalysis of extremely compact, caged trialkylphosphines (SMAPs) in the form of molecules or silica–supported materials are described. The new phosphines are air–stable despite their strongly electron–rich character. Soluble phosphine Ph–SMAP showed high ligand performance in the Rh–catalyzed hydrosilylation and hydrogenation of ketones. The silica–supported SMAP (Silica–SMAP) displayed a unique coordination behavior to form 1:1 P–metal complexes, which appeared to be useful as platforms to create highly active catalytic centers. As a result, Silica–SMAP enabled the Rh–catalyzed hydrosilylation and hydrogenation of extremely hindered ketones such as di–tert–butyl ketone as well as Ir–catalyzed directed ortho–borylation of functionalized arenes with a broad substrate scope.
• Gold(I) Hydride Intermediate in Catalysis: Dehydrogenative Alcohol Silylation Catalyzed by Gold(I) Complex

  Hajime Ito, Tomohisa Saito, Takahiro Miyahara, Chongmin Zhong, Masaya Sawamura

  ORGANOMETALLICS 28 (16) 4829 - 4840 0276-7333 2009/08 [Refereed][Not invited]
   

  Gold hydride is a rare transition-metal species. Despite the fact that gold hydrides may be key intermediates in several gold-catalyzed reactions, their chemical properties are not well understood. We report the synthesis, characterization, and catalytic properties of gold(I) hydride species that play an important role in a gold(I)-catalyzed dehydrogenative alcohol silylation. Tricoordinated complexes AuCl(xantphos) (1a) and AuCl(xy-xantphos) (1b) were prepared and characterized by (1)H and (31)P{(1)H} NMR measurements and X-ray crystallography. Gold(I) hydride species 6b generated from the reaction between 1b and PhMe(2)SiH (4b) in CDCl(3) was characterized by (1)H and (31)P NMR measurements and ESI-MS spectrometry. NMR and kinetic studies reveald that the reaction mechanism involves the gold(I) hydride species as a key intermediate. The high catalytic activities of 1a and 1b in dehydrogenative alcohol silylation are explained by the stability of the tricoordinated chelating structure and the activation of the Au-Cl bond induced by the stereoelectronic effect of the coordinating phosphorus atoms. This study reports the first example of a gold(I) hydride complex that exhibits catalytic activity.
• Cu(I)-Catalyzed Intramolecular Hydroamination of Unactivated Alkenes Bearing a Primary or Secondary Amino Group in Alcoholic Solvents

  Hirohisa Ohmiya, Toshimitsu Moriya, Masaya Sawamura

  ORGANIC LETTERS 11 (10) 2145 - 2147 1523-7060 2009/05 [Refereed][Not invited]
   

  The Cu-Xantphos system [Cu(O-t-Bu)-Xantphos, 10-15 mol %] catalyzes the intramolecular hydroamination of unactivated terminal alkenes bearing an unprotected aminoalkyl substituent in alcoholic solvents, giving pyrrolidine and piperidine derivatives in excellent yields. This system is applicable to both primary and secondary amines and tolerates a variety of functional groups.
• Directed Ortho Borylation of Functionalized Arenes Catalyzed by a Silica-Supported Compact Phosphine-Iridium System

  Soichiro Kawamorita, Hirohisa Ohmiya, Kenji Hara, Atsushi Fukuoka, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 131 (14) 5058 - + 0002-7863 2009/04 [Refereed][Not invited]
   

  An immobilized monophosphine-Ir system, which was prepared in situ from [Ir(OMe)(cod)](2) and a silica-supported, compact phosphine, showed high activities and selectivities for the borylation of aromatic C-H bonds with bis(pinacolato)diboron. This system was effective not only for the borylation of benzene but also for the ortho borylation of arenes with directing groups, such as ester, amide, sulfonate, acetal, alkoxymethyl, and chloro groups, under mild reaction conditions.
• The synthesis of allenes by Cu(I)-catalyzed regio- and stereoselective reduction of propargylic carbonates with hydrosilanes

  Chongmin Zhong, Yusuke Sasaki, Hajime Ito, Masaya Sawamura

  CHEMICAL COMMUNICATIONS (39) 5850 - 5852 1359-7345 2009 [Refereed][Not invited]
   

  Cu(I)-catalyzed anti-S(N)2'-type reduction of internal propargylic carbonates with hydrosilanes affords various di- and trisubstituted allenes with high regioselectivities; the reactions are compatible with functional groups and work efficiently for the synthesis of optically-active allenes.
• Synthesis of Silica-Supported Compact Phosphines and Their Application to Rhodium-Catalyzed Hydrosilylation of Hindered Ketones with Triorganosilanes

  Go Hamasaka, Soichiro Kawamorita, Atsuko Ochida, Ryuto Akiyama, Kenji Hara, Atsushi Fukuoka, Kiyotaka Asakura, Wang Jae Chun, Hirohisa Ohmiya, Masaya Sawamura

  ORGANOMETALLICS 27 (24) 6495 - 6506 0276-7333 2008/12 [Refereed][Not invited]
   

  Solid-supported phosphine ligands silica-SMAPs {[silica gel 60N]-SMAP (1a) or [CARiACT Q-10]-SMAP (1b)}, which are composed of a caged, compact trialkylphosphine (SMAP) as a ligand and silica gel (silica get 60N or CARiACT Q-10) as a support,'were synthesized through surface functionalization. The supported phosphines (1a,b) were structurally characterized by solid-state (13)C, (29)Si, and (31)P cross-polarization/magic angle spinning (CP/MAS) NMR spectroscopies and N(2) adsorption measurements. Complexation of 1a,b with [RhCl(cod)](2) afforded a mono(phosphine)-rhodium complex Silica-SMAP-RhCl(cod) exclusively, even in the presence of excess ligands, as proved by solid-state (13)C and (31)P CP/MAS NMR spectroscopies and Rh K-edged X-ray'absorption fine structure (XAFS) measurements. Heterogeneous catalysts that were prepared from [RhCl(C(2)H(4))(2)](2) and 1a,b showed exceptionally high catalytic activities for the reaction of sterically hindered ketones (including di-tertbutyl ketone) and triorganosi lanes such as Et(3)SiH and (t-Bu)Me(2)SiH. The catalyst from 1b showed no leaching of rhodium after reaction and was reusable without decrease of the activity.
• Palladium-Catalyzed gamma-Selective and Stereospecific Allyl-Aryl Coupling between Allylic Acetates and Arylboronic Acids

  Hirohisa Ohmiya, Yusuke Makida, Tatsunori Tanaka, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 130 (51) 17276 - + 0002-7863 2008/12 [Refereed][Not invited]
   

  Allyl-aryl coupling between allylic acetates and arylboronic acids took place in the presence of catalytic amounts of Pd(OAc)(2), 1,10-phenanthroline, and AgSbF(6) with high gamma-selectivity and EIZ-selectivity, The reaction of an optically active allylic acetates with an alpha-stereogenic center proceeded with excellent alpha-to-gamma chirality transfer with syn-selectivity and gave the corresponding optically active allyl-aryl coupling products with a stereogenic center at the benzylic position.
• Copper(I)-Catalyzed Substitution of Propargylic Carbonates with Diboron: Selective Synthesis of Multisubstituted Allenylboronates

  Hajime Ito, Yusuke Sasaki, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 130 (47) 15774 - + 0002-7863 2008/11 [Refereed][Not invited]
   

  A versatile synthetic method for the preparation of the allenylboronates, Cu(I)-catalyzed reaction of propargylic carbonates with a diboron, is described. A Cu(O-t-Bu)-Xantphos catalyst system was effective for the preparation of various allenylboron compounds, allenylboronates with different substitution patterns, those with functional groups, and an axially chiral one. The Lewis acid promoted stereoselective addition to aldehydes leading to homopropargylic alcohols showed the usefulness of the new allenylboronates.
• Synthesis, Properties, and Catalytic Applications of Caged, Compact Trialkylphosphine 4-Phenyl-1-phospha-4-silabicyclo[2.2.2]octane

  Atsuko Ochida, Go Hamasaka, Yoshihiro Yamauchi, Soichiro Kawamorita, Naoya Oshima, Kenji Hara, Hirohisa Ohmiya, Masaya Sawamura

  ORGANOMETALLICS 27 (21) 5494 - 5503 0276-7333 2008/11 [Refereed][Not invited]
   

  Synthesis, properties, and catalytic applications of a caged trialkylphosphine ligand with Me(3)P-like steric and electronic characters, 4-phenyl-1-phospha-4-silabicyclo[2.2.2] octane (Ph-SMAP), are reported. Given a phenyl group at the silicon atom. the Ph-SMAP ligand displayed nonvolatility with retention of Me3P-like steric and electronic properties. The new ligand is air-stable, crystalline, and easy to handle. Single-crystal X-ray diffraction analyses of Ph-SMAP and its coordination compounds such as borane, rhodium(I), and Pt(II) complexes revealed a rigid, linear structural feature of the Ph-SMAP framework. DFT calculations [B3LYP/6-31G(d,p)] indicated that the electron-donating ability of Ph-SMAP is slightly stronger than that of Me(3)P and that replacement of Si atom of Ph-SMAP with a carbon atom drastically decreases the donor power. The Ph-SMAP ligand markedly accelerated the rhodium-catalyzed hydrosilylation and hydrogenation of ketones as compared with the effect of conventional phosphine ligands such as Me(3)P, Bu(3)P, (t-Bu)(3)P, and PPh(3), when it was used in combination with [{RhCl (C(2)H(4))(2)}(2)] and [Rh(OMe)(cod)], respectively, with P/Rh ratio of 1:1.
• Cyclization of Nonterminal Alkynic beta-Keto Esters Catalyzed by Gold(I) Complex with a Semihollow, End-Capped Triethynylphosphine Ligand

  Hideto Ito, Yusuke Makida, Atsuko Ochida, Hirohisa Ohmiya, Masaya Sawamura

  ORGANIC LETTERS 10 (21) 5051 - 5054 1523-7060 2008/11 [Refereed][Not invited]
   

  A cationic gold(l) complex with a semihollow-shaped trialkynylphosphine catalyzed 5-exo-dig and 6-endo-dig cyclizations of various internal alkynic beta-keto esters, showing a marked advantage over a gold(I)-PPh(3) complex with respect to the rates of the reactions and the product yields. It is proposed that the gold-bound alkynic substrate in a catalytic pocket must be somewhat folded and that such a steric effect makes the carbon-carbon bond formation entropically more favorable.
• Enantioselective Addition of Terminal Alkynes to Aromatic Aldehydes Catalyzed by Copper(I) Complexes with Wide-Bite-Angle Chiral Bisphosphine Ligands: Optimization, Scope, and Mechanistic Studies

  Yohsuke Asano, Hajime Ito, Kenji Hara, Masaya Sawamura

  ORGANOMETALLICS 27 (22) 5984 - 5996 0276-7333 2008/11 [Refereed][Not invited]
   

  The addition of terminal alkynes to aromatic aldehydes was carried out in t-BuOH under mild conditions in the presence of a Cu-phosphine complex, which was prepared in situ from Cu(O-t-Bu) and TRAP chiral bisphosphine, to yield enantiomerically enriched propargyl alcohols with moderate enantioselectivities. Studies on the screening of various ligands showed that wide bite angles of bisphosphine ligands are important for the Cu catalysis. According to the analysis of stoichiometric reactions, the reaction presumably involves the nucleophilic addition of a TRAP-coordinated Cu(I) acetylide to an aldehyde: The alcoholic solvent participates in the addition through coordination to the Cu center and simultaneous protonation of the carbonyl oxygen. The C-C bond-forming addition step is reversible with a strong preference for the backward reaction.
• Hydrogenation of Hindered Ketones Catalyzed by a Silica-Supported Compact Phosphine-Rh System

  Soichiro Kawamorita, Go Hamasaka, Hirohisa Ohmiya, Kenji Hara, Atsushi Fukuoka, Masaya Sawamura

  ORGANIC LETTERS 10 (20) 4697 - 4700 1523-7060 2008/10 [Refereed][Not invited]
   

  A heterogeneous mono(phosphine)-Rh catalyst system silica-SMAP-Rh(OMe)(cod), where silica-SMAP stands for a caged, compact trialkylphosphine (SMAP) supported on silica gel, showed broad applicability toward the hydrogenation of hindered ketones. Doubly a-branched ketones such as diisopropyl ketone was hydrogenated under nearly atmospheric conditions. Di-tert-butyl ketone could be hydrogenated under more forcing conditions.
• Conductance of single 1,4-benzenediamine molecule bridging between Au and Pt electrodes

  Manabu Kiguchi, Shinichi Miura, Takuya Takahashi, Kenji Hara, Masaya Sawamura, Kei Murakoshi

  JOURNAL OF PHYSICAL CHEMISTRY C 112 (35) 13349 - 13352 1932-7447 2008/09 [Refereed][Not invited]
   

  We investigated the single 1,4-benzenediamine molecule bridging between Au or Pt electrodes. The conductances of the molecular junctions with the Au-NH2 and Pt-NH2 bonds (Au-NH2 and Pt-NH2 molecular junctions) were 1 x 10(-1) Go (2e(2)/h) and 5 x 10(-3) G(0), respectively. The stretching lengths of the Au-NH2 and Pt-NH2 molecular junctions were 0.03 and 0.07 nm, respectively. The conductance value of the Au-NH2 molecular junction was unexpectedly larger than the value evaluated with the density of states of the metal electrodes and the molecule-metal bond strength, which have been discussed before. The large conductance value could be explained by the small energy difference between metal and molecular orbitals (Delta E) and the high degree of pi-conjugation (P) of the Au-NH2 molecular junction, which would be unique characteristics of the Au-NH2 bond. The present Study showed the importance of these two factors (Delta E, P) in studying the conductance of the single molecualr junction.
• Reversible mechanochromic luminescence of [(C(6)F(5)Au)(2)(mu-1,4-diisocyanobenzene)]

  Hajime Ito, Tomohisa Saito, Naoya Oshima, Noboru Kitamura, Shoji Ishizaka, Yukio Hinatsu, Makoto Wakeshima, Masako Kato, Kiyoshi Tsuge, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 130 (31) 10044 - + 0002-7863 2008/08 [Refereed][Not invited]
   

  Reversible mechanotronic luminescence of [(C(6)F(5)Au)(2)(mu-1,4-diisocyanobenzene)] is reported. Grinding of the complex induced a photoluminescent color change, which was restored by exposure to a solvent. This cycle was repeated 20 times with no color degradation in the emissions. Their optical properties, X-ray crystallographic analysis, IR, and XRD measurements strongly suggested that the change in the molecular arrangement is responsible for this mechanochromic property. Intermolecular aurophilic bondings presumably play a key role in the altered emission.
• Synthesis of metal fullerene complexes by the use of fullerene halides

  Yutaka Matsuo, Yoichiro Kuninobu, Ayako Muramatsu, Masaya Sawamura, Eiichi Nakamura

  ORGANOMETALLICS 27 (14) 3403 - 3409 0276-7333 2008/07 [Refereed][Not invited]
   

  K(C60R5) (1, R = Me, Ph) was generated by deprotonation Of C60R5H (2) and allowed to react with N-fluoropyridinium triflate and N-chloro- and N-bromosuccinimide in benzene at 25 degrees C for 10 min to obtain halogenated fullerenes C60R5X (3a: R = Me, X = F; 3b: R = Me, X = Cl; 3c: R = Me, X = Br; 4a: R = Ph, X = F; 4b: R = Ph, X = Cl, 4c: R = Ph, X = Br) in good yield. The pentamethyl[60]fullerene halides are useful for the synthesis of a variety of eta(5)-fullerene metal complexes. The reaction of the fullerene bromide 3c with the low-valent transition metal complexes Na[Re(CO)(4)] Fe(CO)(5), Ru-3(CO)(12), and Na[Co(Co)(4)] gave Re(eta(5)-C60Me5)(CO3) (5), Fe(eta(5)-C60Me5)Br(CO)(2) (6), Ru(eta(5)-C60Me5)Br(CO)(2) (7), and CO(eta(5)-C60Me5)(CO)(2) (8), respectively. The structures of halide 3c and rhenium complex 5 were determined by X-ray crystallography. Electrochemical measurements on A and 3c were also performed. The iron complex 6 was converted into Fe(eta(5)-C60Me5)C-P (9), Fe(eta(5)-C60Me5)Me(CO)(2) (10), Fe(eta(5)-C60Me5)(CO)(2)(CCH) (11), and Fe(eta(5)-C60Me5)CO)(2)(CCPh) (12), by ligand exchange reactions.
• Copper-catalyzed substitution of allylic carbonates with diboron: A new approach to allylboronate synthesis

  Hajime Ito, Shinichiro Ito, Yusuke Sasaki, Kou Matsuura, Masaya Sawamura

  PURE AND APPLIED CHEMISTRY 80 (5) 1039 - 1045 0033-4545 2008/05 [Refereed][Not invited]
   

  Copper-catalyzed gamma-selective substitution of allylic carbonates with diboron provides a new method for the efficient synthesis of allylboronates. Optically active a-chiral allylboronates were synthesized through the reaction of chiral allylic carbonates with bis(pinacolato)diboron in the presence of achiral Cu(I)-catalyst with highly efficient chirality transfer. Additionally, in the presence of a chiral Cu(I) catalyst, optically active alpha-chiral allylboronates were obtained with >90 % ee through the reaction of prochiral substrates with the diboron.
• Self-assembled monolayers of compact phosphanes with alkanethiolate pendant groups: Remarkable reusability and substrate selectivity in Rh catalysis

  Kenji Hara, Ryuto Akiyama, Satoru Takakusagi, Kohei Uosaki, Toru Yoshino, Hiroyuki Kagi, Masaya Sawamura

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 47 (30) 5627 - 5630 1433-7851 2008 [Refereed][Not invited]
  
• Synthesis of optically active boron-silicon bifunctional cyclopropane derivatives through enantioselective copper(I)-catalyzed reaction of allylic carbonates with a diboron derivative

  Hajime Ito, Yuki Kosaka, Kousuke Nonoyama, Yusuke Sasaki, Masaya Sawamura

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 47 (39) 7424 - 7427 1433-7851 2008 [Refereed][Not invited]
  
• Copper-catalyzed enantioselective substitution of allylic carbonates with diboron: An efficient route to optically active alpha-chiral allylboronates

  Hajime Ito, Shinichiro Ito, Yusuke Sasaki, Kou Matsuura, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 129 (48) 14856 - + 0002-7863 2007/12 [Refereed][Not invited]
   

  A method for the synthesis of alpha-chiral allylboronates featuring the Cu(I)-catalyzed enantioselective substitution of readily available allylic carbonates with a diboron is described. Using this method, various alpha-chiral allylboronates, including functionalized allylboronates, were successfully synthesized, with high enantiomeric purity.
• Construction of self-assembled monolayer terminated with N-heterocyclic carbene-rhodium(I) complex moiety

  Kenji Hara, Keiji Iwahashi, Satoru Takakusagi, Kohei Uosaki, Masaya Sawamura

  SURFACE SCIENCE 601 (22) 5127 - 5132 0039-6028 2007/11 [Refereed][Not invited]
   

  Functionalization of self-assembled monolayer (SAM) of alkanethiolate with metal containing unit is one of the versatile methods to obtain functional surfaces such as heterogeneous catalysts. However, organic molecules that strongly bind to transition metals at SAM terminal are limited. Recently N-heterocyclic carbenes (NHCs) such as cyclic diaminocarbenes have emerged as strongly a-donating ligands forming a robust bond with broad spectrum of transition metals. In the present study, for the purpose of establishment of a new robust basement for heterogeneous metal catalysts, a SAM of the alkanethiolate terminated with NHC-rhodium(I) complex moiety was prepared by utilizing a newly designed disulfide molecule bearing NHC-metal complex terminals. X-ray photoelectron spectroscopy (XPS) analysis and angle resolved XPS measurement revealed successful formation of the Rh-complex-terminated SAM on a gold substrate. Infrared reflection absorption spectroscopy (IRRAS) analysis suggested that the linker methylene chains connecting the rhodium complex moiety and the gold surface are in a loosely packed structure. This unique chemical species, NHC, would be a promising candidate as a basement for the construction of functional surface. (C) 2007 Elsevier B.V. All rights reserved.
• Synthesis and structural characterization of a tetranuclear platinum(II) metallamacrocycle containing 1,3-diisocyanoarene ligands

  Hajime Ito, Tsuyoshi Maeda, Masaya Sawamura

  BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 80 (10) 1981 - 1986 0009-2673 2007/10 [Refereed][Not invited]
   

  A new tetranuclear platinum(II) metallamacrocycle, including four 1,3-diisocyanoarene ligands, was synthesized and characterized. The reaction Of PtI2(cod) with an equimolar amount of the 1,3-diisocyanoarene ligand in dichloromethane under diluted conditions gave the metallamacrocycle [(PtI2)(4)(1,3-diisocyanoarene)(4)], X-ray crystallographic analysis showed that the complex adopted a square ring structure with trans arrangement of coordinated isocyanides around the Pt atoms. GPC, ESI-MS, IR, and NMR analysis of the metallamacrocycle showed that the tetranuclear macrocyclic scaffold was maintained in solution.
• Enantioselective addition of terminal alkynes to aldehydes catalyzed by a Cu(I)-TRAP complex

  Yohsuke Asano, Kenji Hara, Hajime Ito, Masaya Sawamura

  ORGANIC LETTERS 9 (20) 3901 - 3904 1523-7060 2007/09 [Refereed][Not invited]
   

  The addition of terminal alkynes to aromatic aldehydes was carried out under mild conditions in the presence of a Cu-phosphine complex, which was prepared in situ from Cu(O-t-Bu) and TRAP chiral bisphosphine, to yield enantiomerically enriched propargyl alcohols with moderate enantioselectivities. Furthermore, according to stoichiometric reactions, the reaction presumably involves the addition of a TRAP-coordinated Cu(l) acetylide to an aldehyde.
• Conductance of single 1,4-disubstituted benzene molecules anchored to Pt electrodes

  Manabu Kiguchi, Shinichi Miura, Kenji Hara, Masaya Sawamura, Kei Murakoshi

  APPLIED PHYSICS LETTERS 91 (5) 0003-6951 2007/07 [Refereed][Not invited]
   

  The authors have studied the conductance of a 1,4-disubstituted isocyanide(-NC) or thiol(-SH) benzene molecule anchored to two Pt electrodes. A single molecular junction showing a well-defined conductance value (similar to 3x10(-2)G(0), G(0)=2e(2)/h) was fabricated with the Pt electrodes. The conductance of the molecular junction was one order higher than the previously documented value using Au electrodes. These observations could be explained by differences in the local density of states of the contact metal atom at the Fermi level and the extent of the hybridization and energy difference between the molecular and metal orbitals. Further insight into the binding strengths of the metal-anchoring group bond was obtained by statistically analyzing the stretching length of the molecular junction. (c) 2007 American Institute of Physics.
• Phosphorus ligands with a large cavity: Synthesis of triethynylphosphines with bulky end caps and application to the rhodium-catalyzed hydrosilylation of ketones

  Atsuko Ochida, Masaya Sawamura

  CHEMISTRY-AN ASIAN JOURNAL 2 (5) 609 - 618 1861-4728 2007 [Refereed][Not invited]
   

  Trialkynylphosphines substituted with bulky triarylsilyl groups at the alkyne termini were synthesized. The new phosphines P(C equivalent to CSiAr3,)3 (Ar = 3,5-tBu(2)-4-MeOC6H2, 3,5-(Me3Si)(2)C6H3) are uncrowded near the phosphorus atom but bulky in the distal region. As a result, they contain a large cavity, at the bottom of which the phosphine lone-pair electrons are located. The compounds are stable to oxidation by air and hydrolysis. DFT calculations suggested that the triethynylphosphines are good pi-acceptor ligands, comparable with P(OAr)(3). ne trialkynylphosphines reacted with [{RhCl(cod)}(2)] (P/Rh = 1.1:1) to give selectively the monophosphine-rhodium complex [RhCl(cod)P(C CSiAr3)(3)]. X-ray crystal-structure analysis revealed that the {RhCl(cod)} fragment is fully accommodated by the cavity of the phosphine ligand. Compared to the effect of analogues with smaller end caps and PPh3, the trialkynylphosphines accelerated markedly the rhodium-catalyzed hydrosilylation of ketones with a trioganosilane. It is proposed that the higher catalytic activity observed with the holey phosphines is a result of the preferential formation of a monophosphine-rhodium species.
• Monocoordinating, compact phosphane immobilized on silica surface: Application to rhodium-catalyzed hydrosilylation of hindered ketones

  Go Hamasaka, Atsuko Ochida, Kenji Hara, Masaya Sawamura

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 46 (28) 5381 - 5383 1433-7851 2007 [Refereed][Not invited]
  
• Functionalization of silicon surfaces with catalytically active Pd complexes and application to the aerobic oxidation of benzylic alcohols

  Kenji Hara, Shinobu Tayama, Hidekazu Kano, Takuya Masuda, Satoru Takakusagi, Toshihiro Kondo, Kohei Uosaki, Masaya Sawamura

  CHEMICAL COMMUNICATIONS (41) 4280 - 4282 1359-7345 2007 [Refereed][Not invited]
   

  A single-crystal silicon surface was modified with a bisoxazoline-Pd molecular layer and utilized as a highly efficient (catalyst turnover number up to 780 000, 110 degrees C, 72 h) and recyclable catalyst in the aerobic oxidation of benzylic alcohols.
• 20pWH-12 Effect of end group of single 1,4 di-substituted benzene molecule bridging metal electrodes

  Miura S., Kiguchi M., Hara K., Sawamura M., Murakoshi K.

  Meeting Abstracts of the Physical Society of Japan 一般社団法人 日本物理学会 62.1.4 918  2007
• Design and synthesis of isocyanide Ligands for catalysis: Application to rh-catalyzed hydrosilylation of ketones

  Hajime Ito, Takayuki Kato, Masaya Sawamura

  CHEMISTRY-AN ASIAN JOURNAL 2 (11) 1436 - 1446 1861-4728 2007 [Refereed][Not invited]
   

  New isocyanide ligands with meta-terphenyl backbones were synthesized. 2,6-Bis[3,5-bis(trimethylsilyl)-phenyl]-4-methylphenyl isocyanide exhibited the highest rate acceleration in rhodium-catalyzed hydrosilylation among other isocyanide and phosphine ligands tested in this study. H-1 NMR spectroscopic studies on the coordination behavior of the new ligands to [Rh(cod)(2)]BF4 indicated that 2,6-bis-[3,5-bis(trimethylsilyl)phenyl]-4-methylphenyl isocyanide exclusively forms the biscoordinated rhodium-isocyanide complex, whereas less sterically demanding isocyanide ligands predominantly form tetracoordinated rhodium-isocyanide complexes. FTIR and C-13 NMR spectroscopic studies on the hydrosilylation reaction mixture with the rhodium-isocyanide catalyst showed that the major catalytic species responsible for the hydrosilylation activity is the Rh complex coordinated with the isocyanide ligand. DFT calculations of model compounds revealed the higher affinity of isocyanides for rhodium relative to phosphines. The combined effect of high ligand affinity for the rhodium atom and the bulkiness of the ligand, which facilitates the formation of a catalytically active, monoisocyanide-rhodium species, is proposed to account for the catalytic efficiency of the rhodium-bulky isocyanide system in hydrosilylation.
• Using triethynylphosphine ligands bearing bulky end caps to create a holey catalytic environment: Application to gold(I)-catalyzed alkyne cyclizations

  Atsuko Ochida, Hideto Ito, Masaya Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 128 (51) 16486 - 16487 0002-7863 2006/12 [Refereed][Not invited]
  
• Ring carbon functionalization of N-heterocyclic carbene ligand with ester groups. Electronic effect of ester groups on coordination properties

  Kenji Hara, Yoshikazu Kanamori, Masaya Sawamura

  BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 79 (11) 1781 - 1786 0009-2673 2006/11 [Refereed][Not invited]
   

  Palladium complexes with an imidazol-2-ylidene ligand functionalized with ester groups at its 4,5-positions were synthesized from a readily available imidazole derivative. or-Donation from the carbene ligand to the palladium atom is considerably weakened by functionalization with the two ester moieties.
• Conductance of a single molecule anchored by an isocyanide substituent to gold electrodes

  Manabu Kiguchi, Shinichi Miura, Kenji Hara, Masaya Sawamura, Kei Murakoshi

  APPLIED PHYSICS LETTERS 89 (21) 0003-6951 2006/11 [Refereed][Not invited]
   

  The effect of anchoring group on the electrical conductance of a single molecule bridging two Au electrodes was studied using disubstituted [isocyanide (CN-), thiol (S-), or cyanide (NC-)] benzene. The conductance of a single Au/1,4-diisocyanobenzene/Au junction anchored by isocyanide via a C atom (junction with the Au-CN bond) was 3x10(-3)G(0)(=2e(2)/h). The value was comparable to 4x10(-3)G(0) of a single Au/1,4-benzenedithiol/Au junction with the Au-S bond. The Au/1,4-dicyanobenzene/Au molecular junction with the Au-NC bond did not show well-defined conductance values. The metal-molecule bond strength was estimated by the distance over which the molecular junction was stretched before breakdown. The stretched length of the molecular junction with the Au-CN bond was comparable to that of the Au junction, indicating that the Au-CN bond was stronger than the Au-Au bond. (c) 2006 American Institute of Physics.
• Synthesis of new bulky isocyanide ligands and their use for Rh-catalyzed hydrosilylation

  Hajime Ito, Takayuki Kato, Masaya Sawamura

  CHEMISTRY LETTERS 35 (9) 1038 - 1039 0366-7022 2006/09 [Refereed][Not invited]
   

  Bulky isocyanide ligands having meta-terphenyl backbone were developed. Their usefulness as a supporting ligand in catalysis was illustrated by the application to the rhodium-catalyzed hydrosilylation of cyclohexanone. The combined effect of the high ligand affinity to the rhodium atom and the ligand bulkiness to facilitate the formation of a catalytically active, monoligated isocyanide-rhodium species was proposed.
• Cyclic diaminocarbene-rhodium(I) complex tethered to disulfide: Synthesis and application to gold surface modification

  Kenji Hara, Keiji Iwahashi, Yoshikazu Kanamori, Satoshi Naito, Satoru Takakusagi, Kohei Uosaki, Masaya Sawamura

  CHEMISTRY LETTERS 35 (8) 870 - 871 0366-7022 2006/08 [Refereed][Not invited]
   

  A dimeric N-heterocyclic carbene (NHC)-rhodium(I) complex connected with a long chain dialkyl disulfide linker was synthesized, and used for the preparation of a Rh-modified alkane thiolate monolayer on a gold surface.
• Electronically tunable compact trialkylphosphines: SMAPs-bridged bicyclic phosphines

  A Ochida, S Ito, T Miyahara, H Ito, M Sawamura

  CHEMISTRY LETTERS 35 (3) 294 - 295 0366-7022 2006/03 [Refereed][Not invited]
   

  A series of silicon-constrained monodentate trialkylphosphines SMAPs bearing a Si substituent with diverse electronic natures were synthesized. DFT calculations and NMR measurements indicated that these compounds constitute a class of electronically tunable trialkylphosphines. The tunable range of donor power overlaps those of tri(tert-butyl)phosphiiie and monoalkyldiarylphosphines.
• Synthesis and properties of SMAPs 1-phospha-4-silabicyclo[2.2.2]octane derivatives

  Atsuko Ochida, Masaya Sawamura

  ARKIVOC 359 - 369 1424-6376 2006 [Refereed][Not invited]
   

  Synthesis and properties of a new class of trialkylphosphine ligands SMAPs (1-phospha-4-silabicyclo[ 2.2.2] octane derivatives, named after silicon-constrained monodentate alkylphosphine) with Me3P-like steric demand around the phosphorus center are described. A new feature of this class of ligands is the presence of a site for functionalization at the backside of the P-lone pair, which is not the case for Me3P. The SMAP ligands contain phosphorus and silicon atoms at each bridgehead of the bicyclo[ 2.2.2] octane framework. The molecular constraint of the bicyclic framework makes the steric demand around the phosphorus center as small as that of Me3P and projects the P-lone pair and the Si-substituent ( R) in diametrically opposite directions on the straight line defined by the two bridgehead atoms. SMAP derivatives bearing Si substituents with varied electronic natures are obtainable by transforming the parent compound 4-phenyl-phospha-4-silabicyclo[ 2.2.2] octane (Ph-SMAP) through Si - Ph bond cleavage, and they constitute a class of electronically tunable trialkylphosphines. DFT calculations indicated that the parent ligand Ph-SMAP is similar to Me3P in donor power and that the tunable range of the donor power overlaps those of (t-Bu)(3)P and RAr2P ( R: alkyl, Ar: aryl).
• 26pYH-9 Quantized conductance of single 1,4-phenylenediisocyanide molecule bridged between Au electrodes

  Miura Shinichi, Kiguchi Manabu, Hara Kenji, Sawamura Masaya, Murakoshi Kei

  Meeting Abstracts of the Physical Society of Japan 一般社団法人 日本物理学会 61.2.4 776  2006
• Strong counteranion effects on the catalytic activity of cationic silicon Lewis acids in Mukaiyama aldol and Diels-Alder reactions

  K Hara, R Akiyama, M Sawamura

  ORGANIC LETTERS 7 (25) 5621 - 5623 1523-7060 2005/12 [Refereed][Not invited]
   

  [GRAPHICS] A toluene-coordinated silyl borate, [Et3Si(toluene)]B(C6F5)(4), demonstrated catalytic activities significantly higher than those of Me3SiOTf and Me3SiNTf2 in Mukaiyama aldol and Diels-Alder reactions.
• Copper-catalyzed gamma-selective and stereospecific substitution reaction of allylic carbonates with diboron: Efficient route to chiral allylboron compounds

  H Ito, C Kawakami, M Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 127 (46) 16034 - 16035 0002-7863 2005/11 [Refereed][Not invited]
  
• Gold(I)-phosphine catalyst for the highly chemoselective dehydrogenative silylation of alcohols

  H Ito, K Takagi, T Miyahara, M Sawamura

  ORGANIC LETTERS 7 (14) 3001 - 3004 1523-7060 2005/07 [Refereed][Not invited]
   

  A gold(I) complex of Xantphos AuCl(xantphos) catalyzes the dehydrogenative silylation of alcohols with high chemoselectivity and solvent tolerance. It is selective for the silylation of hydroxyl groups in the presence of alkenes, alkynes, alkyl halides (RCl, RBr), ketones, aldehydes, conjugated enones, esters, and carbamates.
• Versatile dehydrogenative alcohol silylation catalyzed by Cu(I)-phosphine complex

  H Ito, A Watanabe, M Sawamura

  ORGANIC LETTERS 7 (9) 1869 - 1871 1523-7060 2005/04 [Refereed][Not invited]
   

  Cu(I) complexes of xanthane-based diphosphines were versatile catalysts for dehydrogenative alcohol silylation, exhibiting high activity and broad substrate scope. Highly selective silylation of 1-decanol over 2-decanol is possible even with a silylating reagent of small steric demand such as HSiMe2Ph or HSiEt3.
• Multilayer vesicles and vesicle clusters formed by the fullerene-based surfactant C-60(CH3)(5)K

  C Burger, JC Hao, QC Ying, H Isobe, M Sawamura, E Nakamura, B Chu

  JOURNAL OF COLLOID AND INTERFACE SCIENCE 275 (2) 632 - 641 0021-9797 2004/07 [Refereed][Not invited]
   

  The self-assembly behavior of a fullerene-based surfactant, C-60(CH3)(5)K, in water was studied using a combination of static and dynamic light scattering, as well as transmission electron microscopy, and compared to that of the compound C-60(C6H5)(5)K. Both fullerene surfactant systems spontaneously assemble into large vesicles consisting of closed spherical shells formed by bilayers, with critical aggregation concentrations (CAC) lower than 10(-6) g ml(-1). At low concentrations, the aggregate sizes Of C-60(CH3)(5)K (radius R similar to 26.8 nm) and C-60(C6H5)(5)K (R similar to 17.0 nm) were found to be substantially different from each other, showing that the change of the substituents surrounding the polar cyclopentadienide head group makes it possible to control the size of the resulting aggregates. Furthermore, the C-60(CH3)(5)K vesicles were found to exist in two qualitatively different types of aggregation with a critical reaggregation concentration (CRC) located at 3.30 x 10(-6) g ml(-1). Above the CRC, larger aggregates were observed (R similar to 37.6 nm), showing a more complex form of supramolecular aggregation, e.g., in terms of multi-bilayer vesicles and/or of clusters of bilayer vesicles. (C) 2004 Elsevier Inc. All rights reserved.
• Multilayer vesicles and vesicle clusters formed by the fullerene-based surfactant C-60(CH3)(5)K

  C Burger, JC Hao, QC Ying, H Isobe, M Sawamura, E Nakamura, B Chu

  JOURNAL OF COLLOID AND INTERFACE SCIENCE 275 (2) 632 - 641 0021-9797 2004/07 [Not refereed][Not invited]
   

  The self-assembly behavior of a fullerene-based surfactant, C-60(CH3)(5)K, in water was studied using a combination of static and dynamic light scattering, as well as transmission electron microscopy, and compared to that of the compound C-60(C6H5)(5)K. Both fullerene surfactant systems spontaneously assemble into large vesicles consisting of closed spherical shells formed by bilayers, with critical aggregation concentrations (CAC) lower than 10(-6) g ml(-1). At low concentrations, the aggregate sizes Of C-60(CH3)(5)K (radius R similar to 26.8 nm) and C-60(C6H5)(5)K (R similar to 17.0 nm) were found to be substantially different from each other, showing that the change of the substituents surrounding the polar cyclopentadienide head group makes it possible to control the size of the resulting aggregates. Furthermore, the C-60(CH3)(5)K vesicles were found to exist in two qualitatively different types of aggregation with a critical reaggregation concentration (CRC) located at 3.30 x 10(-6) g ml(-1). Above the CRC, larger aggregates were observed (R similar to 37.6 nm), showing a more complex form of supramolecular aggregation, e.g., in terms of multi-bilayer vesicles and/or of clusters of bilayer vesicles. (C) 2004 Elsevier Inc. All rights reserved.
• Creation of hoop- and bowl-shaped benzenoid systems by selective detraction of [60]fullerene conjugation. [10]cyclophenacene and fused corannulene derivatives

  Y Matsuo, K Tahara, M Sawamura, E Nakamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 126 (28) 8725 - 8734 0002-7863 2004/07 [Refereed][Not invited]
   

  Selective penta-addition of a methylcopper reagent followed by addition of a phenylcopper reagent to a suitably modified synthetic intermediate results in creation of 40pi-electron systems-hoop- and bowl-shaped cyclic benzenoid compounds, [10]cyclophenacene, and dibenzo-fused corannulene derivatives. The 40pi-electron cyclophenacene derivatives have been found to be chemically stable, yellow-colored, luminescent (560 nm), and EPR-silent. X-ray crystallographic analysis provided precision structural data sets. The dibenzo-fused corannulene derivatives exhibit blue-green (460 nm) to red (649 nm) fluorescence.
• Nickel, palladium, and platinum complexes of eta(5)-cyclopentadienide C60R5 ligands. Kinetic and thermodynamic stabilization effects of the C60Ph5 ligand

  Y Kuninobu, Y Matsuo, M Toganoh, M Sawamura, E Nakamura

  ORGANOMETALLICS 23 (13) 3259 - 3266 0276-7333 2004/06 [Refereed][Not invited]
   

  The nickel-, palladium-, and platinum-RFCp complexes Ni(eta(5)-RFCp)(eta(3)-allylic) (3b, RFCp = C60R5, R = Me, allylic = methallyl; 4a, R = Ph, allylic = allyl; 4b, R = Ph, allylic = methallyl), Pd(eta(5)-RFCp)(eta(3)-allylic) (7a, R = Me, allylic = allyl; 7b, R Me, allylic = methallyl; 7c, R Me, allylic = crotyl; 8a, R = Ph, allylic = allyl; 8b, R Ph, allylic = methallyl; 8c, R Ph, allylic = crotyl), and Pt(eta(5)-RFCp)(eta(3)-methallyl) (9, R = Me; 10, R = Ph), were synthesized by transmetalation between K(RFCp) (R = Me, Ph) and [Ni(allylic)Br](2), [Pd(allylic)Cl](2), or [Pt(methallyl)Cl](2) in THF at 25 degreesC for 10 min: The nickel-PhFCp complexes 4a,b are unusually more stable toward molecular oxygen than the corresponding simple nickel cyclopentadienides and survive in air for many hours at elevated temperature. The crystal structures and the electrochemical properties of the palladium complexes suggest that the unusual stability of the PhFCp complexes is due to the kinetic stabilization effect of the five Ph groups surrounding the metal atom and the thermodynamic stabilization effect of the electron-withdrawing fullerene moiety, hence suggesting new opportunities for the synthesis of otherwise unstable organometallic compounds.
• Nickel, palladium, and platinum complexes of eta(5)-cyclopentadienide C60R5 ligands. Kinetic and thermodynamic stabilization effects of the C60Ph5 ligand

  Y Kuninobu, Y Matsuo, M Toganoh, M Sawamura, E Nakamura

  ORGANOMETALLICS 23 (13) 3259 - 3266 0276-7333 2004/06 [Not refereed][Not invited]
   

  The nickel-, palladium-, and platinum-RFCp complexes Ni(eta(5)-RFCp)(eta(3)-allylic) (3b, RFCp = C60R5, R = Me, allylic = methallyl; 4a, R = Ph, allylic = allyl; 4b, R = Ph, allylic = methallyl), Pd(eta(5)-RFCp)(eta(3)-allylic) (7a, R = Me, allylic = allyl; 7b, R Me, allylic = methallyl; 7c, R Me, allylic = crotyl; 8a, R = Ph, allylic = allyl; 8b, R Ph, allylic = methallyl; 8c, R Ph, allylic = crotyl), and Pt(eta(5)-RFCp)(eta(3)-methallyl) (9, R = Me; 10, R = Ph), were synthesized by transmetalation between K(RFCp) (R = Me, Ph) and [Ni(allylic)Br](2), [Pd(allylic)Cl](2), or [Pt(methallyl)Cl](2) in THF at 25 degreesC for 10 min: The nickel-PhFCp complexes 4a,b are unusually more stable toward molecular oxygen than the corresponding simple nickel cyclopentadienides and survive in air for many hours at elevated temperature. The crystal structures and the electrochemical properties of the palladium complexes suggest that the unusual stability of the PhFCp complexes is due to the kinetic stabilization effect of the five Ph groups surrounding the metal atom and the thermodynamic stabilization effect of the electron-withdrawing fullerene moiety, hence suggesting new opportunities for the synthesis of otherwise unstable organometallic compounds.
• Nonvolatile Me3P-like P-donor ligand: Synthesis and properties of 4-phenyl-1-phospha-4-silabicyclo[2.2.2]octane

  A Ochida, K Hara, H Ito, M Sawamura

  ORGANIC LETTERS 5 (15) 2671 - 2674 1523-7060 2003/07 [Refereed][Not invited]
   

  [GRAPHICS] A new trialkylphosphine ligand with Me3P-like steric and electronic properties, 4-phenyl-1-phospha-4-silabicyclo[2.2.2]octane (Ph-SMAP), was synthesized. Given a phenyl group at the silicon atom, the Ph-SMAP ligand displayed nonvolatility with retention of Me3P-like properties. The new ligand was air-stable, crystalline, and easy to handle.
• Synthesis, structure, and aromaticity of a hoop-shaped cyclic benzenoid [10]cyclophenacene

  E Nakamura, K Tahara, Y Matsuo, M Sawamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 125 (10) 2834 - 2835 0002-7863 2003/03 [Refereed][Not invited]
  
• Regioselective synthesis of [60]fullerene eta(5)-indenide R3C60- and eta(5)-cyclopentadienide R5C60- bearing different R groups

  M Toganoh, K Suzuki, R Udagawa, A Hirai, M Sawamura, E Nakamura

  ORGANIC & BIOMOLECULAR CHEMISTRY 1 (14) 2604 - 2611 1477-0520 2003 [Refereed][Not invited]
   

  Treatment of a 1,7-diorgano[60]fullerene with Grignard reagents or organocopper reagents affords a [60]fullerene indenide or a [60]fullerene cyclopentadienide regioselectively in good to excellent yields. These reactions gave an insight into the reaction mechanism of the organocopper penta-addition reaction of [60]fullerene, giving [60]fullerene cyclopentadienide in quantitative yield.
• Stacking of conical molecules with a fullerene apex into polar columns in crystals and liquid crystals

  M Sawamura, K Kawai, Y Matsuo, K Kanie, T Kato, E Nakamura

  NATURE 419 (6908) 702 - 705 0028-0836 2002/10 [Refereed][Not invited]
   

  Polar liquid crystalline materials can be used in optical and electronic applications, and recent interest has turned to formation strategies that exploit the shape of polar molecules and their interactions to direct molecular alignment(1,2). For example, banana-shaped molecules align their molecular bent within smectic layers(3), whereas conical molecules should form polar columnar assemblies(4-9). However, the flatness of the conical molecules used until now(4-6,9) and their ability to flip(7,8) have limited the success of this approach to making polar liquid crystalline materials. Here we show that the attachment of five aromatic groups to one pentagon of a C-60 fullerene molecule yields deeply conical molecules that stack into polar columnar assemblies. The stacking is driven by attractive interactions between the spherical fullerene moiety and the hollow cone formed by the five aromatic side groups of a neighbouring molecule in the same column. This packing pattern is maintained when we extend the aromatic groups by attaching flexible aliphatic chains, which yields compounds with thermotropic and lyotropic liquid crystalline properties. In contrast, the previously reported fullerene-containing liquid crystals(10-17) all exhibit thermotropic properties only, and none of them contains the fullerene moiety as a functional part of its mesogen units. Our design strategy should be applicable to other molecules and yield a range of new polar liquid crystalline materials.
• Hybrid of ferrocene and fullerene

  M Sawamura, Y Kuninobu, M Toganoh, Y Matsuo, M Yamanaka, E Nakamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 124 (32) 9354 - 9355 0002-7863 2002/08 [Not refereed][Not invited]
  
• Regioselective penta-addition of 1-alkenyl copper reagent to [60]fullerene. Synthesis of penta-alkenyl FCp ligand

  M Sawamura, N Nagahama, M Toganoh, E Nakamura

  JOURNAL OF ORGANOMETALLIC CHEMISTRY 652 (1-2) 31 - 35 0022-328X 2002/06 [Refereed][Not invited]
   

  We have found the conditions to achieve penta-addition of an alkenyl group to [60]fullerene in good yield with the aid of an RCu-type reagent prepared from the corresponding alkenyllithium reagent. The addition took place regioselectively at the five double bonds surrounding a pentagon in the fullerene and with retention of the stereochemistry of the alkenylcopper reagent. The reaction thus produced a cyclopentadiene embedded in the fullerene core that bears five 1-alkenyl groups (1c-e). (C) 2002 Published by Elsevier Science B,V.
• Regioselective penta-addition of 1-alkenyl copper reagent to [60]fullerene. Synthesis of penta-alkenyl FCp ligand

  M Sawamura, N Nagahama, M Toganoh, E Nakamura

  JOURNAL OF ORGANOMETALLIC CHEMISTRY 652 (1-2) 31 - 35 0022-328X 2002/06 [Not refereed][Not invited]
   

  We have found the conditions to achieve penta-addition of an alkenyl group to [60]fullerene in good yield with the aid of an RCu-type reagent prepared from the corresponding alkenyllithium reagent. The addition took place regioselectively at the five double bonds surrounding a pentagon in the fullerene and with retention of the stereochemistry of the alkenylcopper reagent. The reaction thus produced a cyclopentadiene embedded in the fullerene core that bears five 1-alkenyl groups (1c-e). (C) 2002 Published by Elsevier Science B,V.
• Cu(I)-mediated regioselective tri-addition of Grignard reagent to [70]fullerene. Synthesis of indenyl-type metal ligand embedded into graphitic structure

  M Sawamura, M Toganoh, H Iikura, Y Matsuo, A Hirai, E Nakamura

  JOURNAL OF MATERIALS CHEMISTRY 12 (7) 2109 - 2115 0959-9428 2002 [Refereed][Not invited]
   

  A variety of [70]fullerene derivatives bearing three organic groups C70R3H (1, R = aryl, methyl) have been synthesized in 90-99% isolated yield by the reaction of [70]fullerene with a Grignard reagent in the presence of CuBr.S(CH3)(2). Deprotonation of C70R3H with a metal alkoxide gave the corresponding metal complex M(eta(5)-C70R3) [M = K (2), Tl (3)]. X-ray crystallographic analysis as well as theoretical study revealed the nature of the 68pi-electron ligand, C70R3-.
• Epitaxial growth and electronic structure of a C-60 derivative prepared by using a solution spray technique

  T Shimada, H Nakatani, K Ueno, A Koma, Y Kuninobu, M Sawamura, E Nakamura

  JOURNAL OF APPLIED PHYSICS 90 (1) 209 - 212 0021-8979 2001/07 [Not refereed][Not invited]
   

  We demonstrate and analyze the epitaxial film formation of a molecular material that cannot be evaporated in vacuum due to thermal decomposition. A solution of the material is sprayed onto single crystalline van der Waals surfaces using a pulse valve under controlled vapor pressure of the solvent. Monolayer epitaxial films are obtained and we propose that the growth is mediated by liquid ultrathin films formed on the surface. Molecular arrangement and electronic structure of C-60(CH3)(5)H films are studied by reflection high energy electron diffraction and ultraviolet photoelectron spectroscopy, respectively. The present technique will be useful to study the electronic structure of recently synthesized molecular materials. (C) 2001 American Institute of Physics.
• Spherical bilayer vesicles of fullerene-based surfactants in water: A laser light scattering study

  SQ Zhou, C Burger, B Chu, M Sawamura, N Nagahama, M Toganoh, UE Hackler, H Isobe, E Nakamura

  SCIENCE 291 (5510) 1944 - 1947 0036-8075 2001/03 [Refereed][Not invited]
   

  The low solubility of fullerenes in aqueous solution Limits their applications in biology. By appropriate substitution, the fullerenes can be transformed into stabilized anions that are water soluble and can form targe aggregated structures. A Laser light scattering study of the association behavior of the potassium salt of pentaphenyl fullerene (Ph5C60K) in water revealed that the hydrocarbon anions Ph5C60- associate into bilayers, forming stable spherical vesicles with an average hydrodynamic radius and a radius of gyration of about 17 nanometers at a very Low critical aggregation concentration of Less than 10(-7) moles per Liter. The average aggregation number of associated particles in these large spherical Vesicles is about 1.2 x 10(4).
• Chemistry of eta(5)-fullerene metal complexes

  E Nakamura, M Sawamura

  PURE AND APPLIED CHEMISTRY 73 (2) 355 - 359 0033-4545 2001/02 [Refereed][Not invited]
   

  Treatment of [60]fullerene with an organocopper reagent converts one of the pen tagons of the fullerene into cyclopentadienyl anion through addition of five organic groups on every peripheral carbon atom surrounding the pentagon. Similar treatment of [70]fullerene afforded indenyl anion through regioselective tri-addition of the organic group. These anionic moieties strongly interact with the remainder of the fullerene pi -system, and provide unique opportunity for exploration of organometallic chemistry of a new class of metal cyclopentadienides.
• Half-sandwich metallocene embedded in a spherically extended pi-conjugate system. Synthesis, structure, and electrochemistry of Rh(eta(5)-C60Me5)(CO)(2)

  M Sawamura, Y Kuninobu, E Nakamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 122 (49) 12407 - 12408 0002-7863 2000/12 [Refereed][Not invited]
  
• Catalytic asymmetric hydrogenation of alpha-(acetamido)acrylates using TRAP trans-chelating chiral bisphosphine ligands: Remarkable effects of ligand P-substituent and hydrogen pressure on enantioselectivity

  R Kuwano, M Sawamura, Y Ito

  BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 73 (11) 2571 - 2578 0009-2673 2000/11 [Refereed][Not invited]
   

  The catalytic asymmetric hydrogenation of alpha-(acetamido)acrylates was carried out with the rhodium complexes prepared from [Rh(cod)(2)]BF4 and trans-chelating chiral bisphosphine ligands, (S,S)-2,2'-bis[(R)-1-(dialkylphosphino)ethyl]-1,1'-biferrocenes [(R,R)-(S,S)-TRAPs]. In the reaction of beta -unsubstituted or beta -monosubstituted alpha-(acetamido)acrylates [(E)-RCH=C(NHAc)CO2Me], the selectivity for (R)-hydrogenation product increased with decreasing steric demand of the substrate beta -substituent and the ligand P-substituent as well as decreasing hydrogen pressure. The selectivity for the (R)-product in the reaction with EtTRAP-rhodium catalyst at 60 degreesC and 0.5 kg cm(-2) of hydrogen pressure was as follows: R = H, 96% ee; R = Me, 92% ee; R = Ph, 77% ee; R = i-Pr, 57% ee. The remarkable steric and pressure effects caused a dramatic reversal of enantioselectivity in the reaction of methyl 2-(N-acetylamino)cinnamate (R = Ph). For example, the selectivity of 87% (R) with EtTRAP at 60 degreesC and 0.1 kg cm(-2) of hydrogen pressure has reversed to 92% (S) with i-B uTRAP at 15 degreesC and atmospheric hydrogen pressure. Hydrogenation of the beta,beta -disubstituted alpha-(acetamido) acrylates proceeded smoothly at 15 degreesC and atmospheric hydrogen pressure with high enantioselectivity in favor of the 2S-isomers when EtTRAP or BuTRAP was employed as the chiral ligand.
• Rhodium-catalyzed enantioselective Michael addition of (1-cyanoethyl)phosphonate: Synthesis of optically active phosphonic acid derivatives with phosphorus-substituted quaternary asymmetric carbon center

  M Sawamura, H Hamashima, Y Ito

  BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 73 (11) 2559 - 2562 0009-2673 2000/11 [Not refereed][Not invited]
   

  Asymmetric Michael addition of diethyl (1-cyanoethyl)phosphonate with vinyl ketones or acrylaldehyde in the presence of 0.01 molar amount of a rhodium catalyst prepared in situ from Rh(acac)(CO)(2) and a trans-chelating chiral diphosphine ligand (R,R)-(S,S)-2,2"-bis[1-(diphenylphosphino)ethyl]-1,1"-biferrocene (PhTRAP) in benzene at 3 degreesC gave optically active phosphonates having a phosphorus-substituted quaternary asymmetric carbon center with high enantiomeric excesses (92-93% ee) in high yields. The Michael addition product from acrylaldehyde was converted into an optically active (1-aminoalkyl)phosphonic acid derivative.
• Pentaorgano[60]fullerene R5C60-. A water soluble hydrocarbon anion

  M Sawamura, N Nagahama, M Toganoh, UE Hackler, H Isobe, E Nakamura, SQ Zhou, B Chu

  CHEMISTRY LETTERS (9) 1098 - 1099 0366-7022 2000/09 [Refereed][Not invited]
   

  A new class of hydrocarbon anions, pentaaryl- and penta-methylfullerene anions R5C60- (R = Ph, 4-BuC6H4, 4-PhC6H4, Me) was found to be stable and soluble in water. Atomic force microscopic observation and dynamic light scattering measurements indicated that the potassium salt Ph5C60K in water forms spherical aggregates with an averaged radius of about 17 nm.
• Stepwise synthesis of fullerene cyclopentadienide R5C60- and indenide R3C60-. An approach to fully unsymmetrically substituted derivatives

  M Sawamura, M Toganoh, K Suzuki, A Hirai, H Iikura, E Nakamura

  ORGANIC LETTERS 2 (13) 1919 - 1921 1523-7060 2000/06 [Refereed][Not invited]
   

  Fullerene cyclopentadienide (PhCH2)(2)Ph3C60- and indenide (PhCH2)(2)PhC60-, each bearing two different organic groups, were efficiently synthesized through regioselective reactions of 1,4-(PhCH2)(2)C-60 with an organocopper reagent (PhMgBr/CuBr . SMe2) or a Grignard reagent (PhMgBr) followed by deprotonation with (KOBu)-Bu-t.
• Single-step synthesis of pentaaryl-monohydro[60]fullerenes through fivefold addition of organocopper reagent to C-60

  M Sawamura, H Iikura, T Ohama, UE Hackler, E Nakamura

  JOURNAL OF ORGANOMETALLIC CHEMISTRY 599 (1) 32 - 36 0022-328X 2000/04 [Refereed][Not invited]
   

  The reaction of an organocopper reagent (ArMgBrlCuBr . SMe2) with C-60 was optimized for the fivefold addition forming a novel Cp-type ligand precursor 1,4,11,15,30-pentaaryl-2-hydro[60]fullerene (C60Ar5H, 1), where Ar stands for Ph, 4-CF3C6H4, 4-MeOC6H4, 4-ClC6H4, 4-BuC6H4, 4-PhC6H4, and 1-naphthyl groups. Under the optimized conditions, a large quantity (8.90 g) of C60Ph5H has been synthesized in a single operation. (C) 2000 Elsevier Science S.A. All rights reserved.
• A cage with fullerene end caps

  H Isobe, A Ohbayashi, M Sawamura, E Nakamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 122 (11) 2669 - 2670 0002-7863 2000/03 [Refereed][Not invited]
  
• Synthesis of pentamethyl-monohydro[60]fullerene C60Me5H and its use as cyclopentadienyl-type ligand precursor

  M Sawamura, M Toganoh, Y Kuninobu, S Kato, E Nakamura

  CHEMISTRY LETTERS (3) 270 - 271 0366-7022 2000/03 [Refereed][Not invited]
   

  Pentamethyl-monohydro[60] fullerene C60Me5H has been synthesized through five-fold addition of methylcopper reagent to C-60. The anion C60Me5- generated by deprotonation of C60Me5H forms organometallic complexes with K+ and TI+ ions with stronger metal-carbon interaction than that in the corresponding pentaphenylated ligand C60Ph5-.
• Asymmetric hydrosilylation of ketones using trans-chelating chiral peralkylbisphosphine ligands bearing primary alkyl substituents on phosphorus atoms

  R Kuwano, M Sawamura, J Shirai, M Takahashi, Y Ito

  BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 73 (2) 485 - 496 0009-2673 2000/02 [Refereed][Not invited]
   

  Asymmetric hydrosilylation of simple ketones with diphenylsilane proceeded at -40 degrees C in the presence of a rhodium complex (0.001-0.01 molar amount) coordinated with a trans-chelating chiral bisphosphine ligand bearing linear alkyl substituents on the phosphorus atoms, (R,R)-(S,S)-Et-, Pr-, or BuTRAP, giving the corresponding optically active (S)-econdary alcohols with up to 97% ee. The asymmetric hydrosilylation using TRAP ligands with bulkier P-substituents resulted in much lower enantioselectivities. The EtTRAP-rhodium catalyst was also effective for asymmetric hydrosilylation of keto esters with a coordination site for a rhodium atom (up to 98% ee) Optically active symmetrical diols were obtained with up to 99% ee from the corresponding diketones via the asymmetric reduction using 2.5 molar amounts of diphenylsilane.
• Palladium-catalysed asymmetric [4+2] cycloaddition of vinylallene with 1,3-diene

  M Murakami, R Minamida, K Itami, M Sawamura, Y Ito

  CHEMICAL COMMUNICATIONS (23) 2293 - 2294 1359-7345 2000 [Refereed][Not invited]
   

  A catalytic asymmetric [4 + 2] cycloaddition reaction of a vinylallene with buta-1,3-diene was developed in which a palladium complex modified by a ferrocene-derived chiral monophosphine ligand acted as a template transferring chirality to the product.
• Functionalized fullerene as an artificial vector for transfection

  E Nakamura, H Isobe, N Tomita, M Sawamura, S Jinno, H Okayama

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 39 (23) 4254 - + 1433-7851 2000 [Refereed][Not invited]
  
• Optical resolution of chirally functionalized [60]fullerene through formation of diastereomeric methoxyphenylacetic acid esters

  H Isobe, M Sawamura, E Nakamura

  FULLERENE SCIENCE AND TECHNOLOGY 7 (4) 519 - 528 1064-122X 1999 [Refereed][Not invited]
   

  Optical resolution of chirally functionalized [60]fullerene has been achieved through formation of diastereomeric alpha-methoxyphenylacetic acid (MPA) esters. The diastereomeric ester products were easily separated either by open column silica gel chromatography or by high pressure liquid chromatography (HPLC) with BuckyPrep(R) column.
• Synthesis of pi-indenyl-type fullerene ligand and its metal complexes via quantitative trisarylation of C-70

  M Sawamura, H Iikura, A Hirai, E Nakamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 120 (32) 8285 - 8286 0002-7863 1998/08 [Refereed][Not invited]
  
• Endohedral homoconjugation in cyclopentadiene embedded in C60. Theoretical and electrochemical evidence

  H Iikura, S Mori, M Sawamura, E Nakamura

  JOURNAL OF ORGANIC CHEMISTRY 62 (23) 7912 - 7913 0022-3263 1997/11 [Refereed][Not invited]
  
• Trans-chelating chiral peralkyldiphosphine ligands (R,R)-(S,S)-2,2 ''-bis[1-(dialkylphosphino)ethyl]-1,1 ''-biferrocenes (AlkylTRAPs) and their transition metal complexes

  R Kuwano, M Sawamura, S Okuda, T Asai, Y Ito, M Redon, A Krief

  BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 70 (11) 2807 - 2822 0009-2673 1997/11 [Refereed][Not invited]
   

  New chiral peralkyldiphosphines (S,S)-2,2 "-bis[(R)-1-(dialkylphosphino)ethyl]-1,1 "-biferrocenes ((R,R)-(S,S)-alkylTRAPs) were synthesized from (R)-N,N-dimethyl-1-ferrocenylethylamine in four steps in 38-68% overall yields (MeTRAP: 38%, EtTRAP: 68%, PrTRAP: 53%, BuTRAP: 56%, i-BuTRAP: 51%, i-PrTRAP: 42%). The reactions of alkylTRAP (Et-, Bu-, i-Bu, and i-PrTRAP) with 1 molar amount of PdBr2 gave trans-[PdBr2(alkylTRAP)] in good yields. The X-ray crystal structures of these palladium complexes revealed that alkylTRAPs coordinated to a palladium atom in a trans-chelating manner regardless of the P-alkyl substituents. The structures of palladium complexes of Et-, Bu-, and i-PrTRAP had nearly Ct-symmetry, but that of i-BuTRAP was deviated from Ct-symmetry significantly. AlkylTRAPs also reacted with [PtCl2(MeCN)(2)] and [RhCl(CO)(2)](2), giving the corresponding trans-chelate platinum and rhodium complexes. The crystal structure of trans-[RhCl(CO)(BuTRAP)] revealed that the conformation of the BuTRAP ligand in the complex was almost the same as that in the palladium complex trans-[PdBr2(BuTRAP)].
• Conversion of alkyl halides into alcohols using a near stoichiometric amount of molecular oxygen: An efficient route to O-18- and O-17-labeled alcohols

  M Sawamura, Y Kawaguchi, E Nakamura

  SYNLETT (7) 801 - & 0936-5214 1997/07 [Refereed][Not invited]
   

  In the presence of near stoichiometric amount of molecular oxygen, various alkyl halides were converted to the corresponding alcohols in high yields through aerobic radical reaction promoted by a Bu-2(t-Bu)SnCl/NaBH3CN catalytic system. Isotope-labeled alcohols were prepared with O-18(2) and O-17(2) without loss of the isotopic purities of the starting oxygen gases.
• Synthetic and computational studies on symmetry-defined double cycloaddition of a new tris-annulating reagent to C-60

  H Isobe, H Tokuyama, M Sawamura, E Nakamura

  JOURNAL OF ORGANIC CHEMISTRY 62 (15) 5034 - 5041 0022-3263 1997/07 [Refereed][Not invited]
   

  For the purpose of doubly functionalizing fullerenes, new tris-annulating reagents 2(n) have been developed. The reagents carry, in one molecule, two cyclopropenone acetals which are connected with an n-carbon methylene tether. Upon thermolysis of 2(n) in the presence of C-60, the reagent undergoes [3 + 2] cycloaddition reaction twice in a regio- and stereoselective manner to give C-s and C-2 organofullerenes bearing two cyclopentenone acetals. The selectivity varies as the function of the tether structure. The experiments have shown that, in each series of different tether lengths, one can obtain one or two diastereomeric double adducts out of several structural possibilities. The selectivity of the reaction did not conform to the prediction made on the basis of previous knowledge on intermolecular double additions but was found to be correlated to the conformational strain of the tether moiety, which can be estimated by a newly developed ''double differential protocol''. Systematic studies on the reliability of various computational methods for organofullerenes indicated that certain molecular orbital and molecular mechanics calculations give very reliable structural data while certain others do not.
• Fullerene that binds a metal on the pentagon

  E Nakamura, M Sawamura, W Iikura, S Mori

  PROCEEDINGS OF THE SYMPOSIUM ON RECENT ADVANCES IN THE CHEMISTRY AND PHYSICS OF FULLERENES AND RELATED MATERIALS, VOL 4 97 (14) 298 - 308 1997 [Refereed][Not invited]
  
• Sonochemical, aerobic conversion of alkyl halides into alcohols promoted by trialkyltin halide NaBH3CN catalytic system

  M Sawamura, Y Kawaguchi, K Sato, E Nakamura

  CHEMISTRY LETTERS (8) 705 - 706 0366-7022 1997 [Refereed][Not invited]
   

  Under sonochemical conditions, various alkyl halides were converted into the corresponding alcohols in high yields through an aerobic radical reaction promoted by trialkyltin halide/NaBH3CN catalytic system.
• Enantioselective allylation of nitro group-stabilized carbanions catalyzed by chiral crown ether phosphine-palladium complexes

  M Sawamura, Y Nakayama, WM Tang, Y Ito

  JOURNAL OF ORGANIC CHEMISTRY 61 (26) 9090 - 9096 0022-3263 1996/12 [Refereed][Not invited]
   

  Enantioselective allylations of alpha-nitro ketones (3) and alpha-nitro esters (15) with allyl acetate were carried out in the presence of 2 equiv of alkali metal fluorides (KF, RbF, CsF) and 1 mol % of palladium catalysts prepared in situ from Pd-2(dba)(3) . CHCl3 and chiral phosphine ligands. Moderate enantioselectivities were observed in the reaction of nitro ketones 3, giving products 4 (4a, 49% ee; 4b, 58% ee; 4c, 44% ee) when rubidium fluoride and ferrocenylphosphine ligands bearing monoaza-15-crown-5 (Ib) or monoaza-18-crown-6 (Ic) moieties were used as a base and a chiral ligand, respectively. Optically active allylation product 4a was converted into 1-methyl-1-azaspiro[4.5]-decan-10-amine (13), a precursor to opioid receptor binding agents. Enantioselectivity in the reaction of nitro esters 15 increased in accord with increasing steric demand of the ester alkyl group (Me < Et < t-Bu). The highest selectivity (80% eel for the reaction of tert-butyl ester 15c was observed when the reaction was carried out at -40 degrees C in the presence of the palladium catalyst with the ligand (Ic) bearing a monoaza-18-crown-6 moiety, RbF (2 equiv), and RbClO4 (1 equiv). The pronounced effect of the crown ether moiety for both enantioselection and rate acceleration can be explained by assuming the formation of a ternary complex involving the crown ether, rubidium cation, and enolate anion at the stereodifferentiating transition state. Optically active nitro ester (R)-16c was converted into (R)-alpha-methylglutamic acid (20).
• The first pentahaptofullerene metal complexes

  M Sawamura, H Iikura, E Nakamura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 118 (50) 12850 - 12851 0002-7863 1996/12 [Refereed][Not invited]
  
• Regio- and diastereocontrolled double cycloaddition to C-60 with new tris-annulating reagents

  H Isobe, H Tokuyama, M Sawamura, E Nakamura

  ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 212 57 - ORGN 0065-7727 1996/08 [Refereed][Not invited]
  
• Regio- and diastereo-controlled double cycloaddition to [60]fullerene: One-step synthesis of Cs and C-2 chiral organofullerenes with new tris-annulating reagents

  E Nakamura, H Isobe, H Tokuyama, M Sawamura

  CHEMICAL COMMUNICATIONS (15) 1747 - 1748 1359-7345 1996/08 [Refereed][Not invited]
   

  Double cycloaddition of new tris-annulation reagents to [60]fullerene creates a tricyclic system constructed on the [60]fullerene sphere, providing Cs symmetric and C-2 chiral non-racemic organofullerenes.
• Enantioselective cycloisomerization of 1,6-enynes catalyzed by chiral diphosphane-palladium complexes

  A Goeke, M Sawamura, R Kuwano, Y Ito

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION IN ENGLISH 35 (6) 662 - 663 0570-0833 1996/04 [Refereed][Not invited]
  
• An enantioselective two-component catalyst system: Rh-Pd-catalyzed allylic alkylation of activated nitriles

  M Sawamura, M Sudoh, Y Ito

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 118 (13) 3309 - 3310 0002-7863 1996/04 [Refereed][Not invited]
  
• Enantioselective Cycloisomerization of 1,6-Enynes Catalyzed by Chiral Diphosphine-Palladium Complexes

  GOEKE A, SAWAMURA M, KUWANO R, ITO Y

  Angewandte Chemie, International Edition in English 35 (6) 662 - 663 1433-7851 1996/04/01 [Refereed][Not invited]
  
• CATALYTIC ASYMMETRIC HYDROGENATION OF DIMETHYL ITACONATE WITH TRANS-CHELATING CHIRAL DIPHOSPHINE LIGANDS TRAP-RHODIUM COMPLEXES

  R KUWANO, M SAWAMURA, Y ITO

  TETRAHEDRON-ASYMMETRY 6 (10) 2521 - 2526 0957-4166 1995/10 [Refereed][Not invited]
   

  Asymmetric hydrogenation of dimethyl itaconate catalyzed by the transchelating chiral diphosphine (R,R)-(S,S)-EtTRAP-rhodium complex gave (S)-dimethyl 2-methylsuccinate with 96% ee. Dimethyl 2-isopropylidenesuccinate, a tetrasubstituted olefin substrate, was also hydrogenated with (R,R)-(S,S)-BuTRAP-rhodium complex in high enantioselectivity (78% ee), but with opposite enantioselection.
• SYNTHESIS AND STRUCTURES OF TRANS-CHELATING CHIRAL DIPHOSPHINE LIGANDS BEARING AROMATIC P-SUBSTITUENTS, (S,S)-(R,R)-2,2''-BIS[1-(DIARYLPHOSPHINO)ETHYL]-1,1''-BIFFERROCENES AND (R,R)-(S,S)-2,2''-BIS[1-(DIARYLPHOSPHINO)ETHYL]-1,1''-BIFFERROCENES (ARYLTRAPS), AND THEIR TRANSITION-METAL COMPLEXES

  M SAWAMURA, H HAMASHIMA, M SUGAWARA, R KUWANO, Y ITO

  ORGANOMETALLICS 14 (10) 4549 - 4558 0276-7333 1995/10 [Refereed][Not invited]
   

  The trans-chelating chiral phosphine ligand (S,S)-(R,R)-2,2 ''-bis[1-(diphenylphosphino)- ethyl]-1,1 ''-biferrocene (la, abbreviated to PhTRAP) was synthesized from (S)-1-(N,N-dimethylamino)ethylferrocene (2) in four steps in 51% overall yield. (R,R)-(S,S)-PhTRAP and other arylTRAP derivatives (Ib, AnisTRAP; Ic, Cl-PhTRAP, Id, FurTRAP; le, Tol-PhTRAP) were synthesized in a similar manner. Through-space P-31-P-31 Spin couplings were observed indirectly in the H-1 and C-13{H-1} NMR spectra of la-e and directly in the P-31{H-1} NMR spectrum of asymmetrical TRAP le, indicating that the two phosphorus atoms of the ligands are in close proximity. Results of NOE experiments showed that PhTRAP is a fairly rigid molecule and in a conformation favorable for trans-chelation. As square planar transition metal complexes bearing arylTRAPs as trans-chelating ligands, trans-[PdX(2){(S,S)-(R,R)-PhTRAP}] (7, X = Pr; 8, X = I; 9, X = Cl), trans-[PtCl2{(R,R)-(S,S)-PhTRAP}] (10), trans-[PtCl2{(S,S)-(R,R)-1e}] (11), trans-[IrCl(CO){(S,S)-(R,R)-PhTRAP}] (12), trans-[RhCl(CO){(S,S)-(R,R)-PhTRAP}] (13), and trans-[RhCl(CO){(S,S)-(R,R)-FurTRAP}] (14) were prepared and fully characterized. X-ray crystal structures were determined for the palladium complex 7 and the rhodium complex 14.
• ENANTIOSELECTIVE HYDROGENATION OF BETA-DISUBSTITUTED ALPHA-ACETAMIDOACRYLATES CATALYZED BY RHODIUM COMPLEXES WITH TRAP TRANS-CHELATING CHIRAL PHOSPHINE-LIGANDS

  M SAWAMURA, R KUWANO, Y ITO

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 117 (37) 9602 - 9603 0002-7863 1995/09 [Refereed][Not invited]
  
• ASYMMETRIC MICHAEL REACTION OF AN ALPHA-CYANO WEINREB AMIDE CATALYZED BY A RHODIUM COMPLEX WITH TRANS-CHELATING CHIRAL DIPHOSPHINE PHTRAP

  M SAWAMURA, H HAMASHIMA, H SHINOTO, Y ITO

  TETRAHEDRON LETTERS 36 (36) 6479 - 6482 0040-4039 1995/09 [Refereed][Not invited]
   

  Asymmetric Michael reaction of N-methoxy-N-methyl-2-cyanopropionamide with vinyl ketones or acrolein in the presence of 0.1-1 mol% of a rhodium catalyst prepared in situ from Rh(acac)(CO)(2) and a trans-chelating chiral diphosphine ligand (S,S)-(R,R)-PhTRAP gave optically active Michael adducts with high enantiomeric excesses (89-94%) in high yields. The adducts with methyl vinyl ketone was transformed into an alpha-cyano aldehyde and ketones with an quarternary asymmetric carbon center through the reaction with LiAlH4 or Grignard reagents.
• SYNTHESIS AND CELLULAR CHARACTERIZATION OF THE DETRANSFORMATION AGENT, (-)-DEPUDECIN

  U SHIMADA, HJ KWON, M SAWAMURA, SL SCHREIBER

  CHEMISTRY & BIOLOGY 2 (8) 517 - 525 1074-5521 1995/08 [Refereed][Not invited]
   

  Background: (-)-Depudecin is a fungal metabolite that reverts the rounded phenotype of NIH3T3 fibroblasts transformed with v-ras and v-src oncogenes to the flat phenotype of the nontransformed parental cells. The mechanism of action of this detransformation agent is unknown. Although depudecin appears to be an excellent molecule; for probing signaling pathways that regulate changes in the cytoskeletal architecture, reagents based on depudecin are not available as it has not yet been successfully synthesized. We therefore set out to synthesize (-)-depudecin. Results: An asymmetric synthesis of(-)-depudecin has been developed. A cell staining assay has been used to reveal the ability of synthetic depudecin, but not several structural variants, to induce a flattened morphology in v-Ha-ras-transformed NIH3T3 cells. This assay also shows depudecin induces an intricate network of actin stress fibers in these cells and in MG63 osteosarcoma cells and reveals the essential role of the epoxide and hydroxyl moieties in depudecin. Cycloheximide and actinomycin D inhibited the ability of depudecin to induce a morphological change, suggesting that both mRNA synthesis and de novo protein synthesis are required for depudecin-mediated suppression of the transformed phenotypes in ras-transformed cells. Conclusions: The synthetic procedure provides access to (-)-depudecin and could be readily modified to produce depudecin-related reagents for the identification of depudecin's cellular target(s). This target appears to be involved in the regulation of the assembly of the actin microfilament component of the cytoskeleton in mammalian cells.
• ASYMMETRIC HYDROSILYLATION OF SYMMETRICAL DIKETONES CATALYZED BY A RHODIUM COMPLEX WITH TRANS-CHELATING CHIRAL DIPHOSPHINE ETTRAP

  R KUWANO, M SAWAMURA, J SHIRAI, M TAKAHASHI, Y ITO

  TETRAHEDRON LETTERS 36 (29) 5239 - 5242 0040-4039 1995/07 [Refereed][Not invited]
   

  Asymmetric hydrosilylation of symmetrical diketones with diphenylsilane in the presence of catalytic amount ([substrate]/[catalyst] = 100) of rhodium complex coordinated with trans-chelating chiral phosphine ligand EtTRAP gave corresponding optically active symmetrical diols with high enantiomeric excesses.
• ASYMMETRIC HYDROSILYLATION OF KETO ESTERS CATALYZED BY A RHODIUM COMPLEX WITH TRANS-CHELATING CHIRAL DIPHOSPHINE ETTRAP

  M SAWAMURA, R KUWANO, J SHIRAI, Y ITO

  SYNLETT (4) 347 - 348 0936-5214 1995/04 [Refereed][Not invited]
   

  Asymmetric hydrosilylation of alpha-, beta-, and gamma-keto esters with diphenylsilane in the presence of 1 mol% of a rhodium catalyst containing trans-chelating chiral phosphine ligand EtTRAP gave optically active alcohols with enantiomeric excesses ranging between 32-93%.
• GOLD(I)-CATALYZED ASYMMETRIC ALDOL REACTION OF N-METHOXY-N-METHYL-ALPHA-ISOCYANOACETAMIDE (ALPHA-ISOCYANO WEINREB AMIDE) - AN EFFICIENT SYNTHESIS OF OPTICALLY-ACTIVE BETA-HYDROXY-ALPHA-AMINO ALDEHYDES AND KETONES

  M SAWAMURA, Y NAKAYAMA, T KATO, Y ITO

  JOURNAL OF ORGANIC CHEMISTRY 60 (6) 1727 - 1732 0022-3263 1995/03 [Refereed][Not invited]
   

  Asymmetric aldol reaction of N-methoxy-N-methyl-alpha-isocyanoacetamide (alpha-isocyano Weinreb amide) with aldehydes [RCHO: R = Ph, Me, i-Pr, (E)-MeCH=CH, (E)-BnOCH(2)CH=CH] in the presence of a gold(I) catalyst prepared in situ from [Au(c-HexNC)(2)]BF4 and chiral ferrocenylphosphine ligand (R)-N-methyl-N-(2-morpholinoethyl)-1-[(S)-1',2-bis(diphenylphosphino)ferrocenyl]ethylamine gave high yields of optically active trans-5-alkyl-2-oxazoline-4-(N-methoxy-N-methylcarboxamides) with high diastereo- and enantioselectivities. The diastereoselectivities (trans:cis) and enantiomeric excesses of the trans-oxazolines for the reaction with 1 mol % of the catalyst are as follows: R = Ph, 97:3, 96% ee; R = Me, 95:5, 97% ee; R = i-Pr, 98:2, 97% ee; R = (E)-MeCH=CH, 97:3; 99% ee; (E)-BnOCH(2)CH=CH, 96:4, 95% ee. These optically active oxazolines were converted to N,O-protected beta-hydroxy-alpha-amino aldehydes and ketone in high yields. An N-protected alpha-amino aldehyde (R = Ph) lacking the beta-hydroxyl group was also obtained through the catalytic hydrogenolysis of the oxazoline.
• ASYMMETRIC MICHAEL REACTION OF ALPHA-CYANO CARBOXYLATES CATALYZED BY A RHODIUM COMPLEX WITH TRANS-CHELATING CHIRAL DIPHOSPHINE PHTRAP

  M SAWAMURA, H HAMASHIMA, Y ITO

  TETRAHEDRON 50 (15) 4439 - 4454 0040-4020 1994/04 [Not refereed][Not invited]
   

  Asymmetric Michael reaction of 2-cyanopropionates with vinyl ketones or acrolein in the presence of 0.1-1 mol% of a rhodium catalyst prepared in situ from RhH(CO)(PPh(3))(3) and a trans-chelating chiral diphosphine ligand (S,S)-(R,R)-PhTRAP in benzene at 3-5 degrees C gave optically active Michael adducts with high enantiomeric excesses (83-93% ee) in high yields. The reaction of 2-cyanopropionate with methacrolein and crotonaldehyde proceeded somewhat slowly, giving diastereomer mixtures in moderate enantioselectivities but in low diastereoselectivities. The reaction of 2-cyanobutyrate and 2-cyano-3-methylbutyrate with acrolein gave corresponding Michael adducts with much lower enantiomeric excesses than that of 2-cyanopropionates. The Michael addition product from acrolein was converted into an optically active alpha-methyl-alpha-amino acid.
• TRANS-CHELATING CHIRAL DIPHOSPHANE LIGANDS BEARING FLEXIBLE P-ALKYL SUBSTITUENTS (ALKYLTRAPS) AND THEIR APPLICATION TO THE RHODIUM-CATALYZED ASYMMETRIC HYDROSILYLATION OF SIMPLE KETONES

  M SAWAMURA, R KUWANO, Y ITO

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION IN ENGLISH 33 (1) 111 - 113 0570-0833 1994/01 [Refereed][Not invited]
  
• Trans-Chelating Chiral Diphosphine Ligands Bearing Flexible P-Alkyl Substituents (Alkyl TRAPs). An Application to Rhodium-Catalyzed Asymmetric Hydrosilylation of Simple Ketones

  SAWAMURA M, KUWANO R, ITO Y

  Angewandte Chemie, International Edition in English 33 (1) 111 - 113 1433-7851 1994 [Not refereed][Not invited]
  
• SYNTHESIS OF OPTICALLY-ACTIVE FERROCENE ANALOGS OF SALICYLIC-ACID DERIVATIVES AND RHODIUM(II)-CATALYZED ASYMMETRIC INTRAMOLECULAR-C-H INSERTION OF ALPHA-DIAZO BETA-KETO-ESTERS USING NEW CHIRAL CARBOXYLATO LIGANDS

  M SAWAMURA, H SASAKI, T NAKATA, Y ITO

  BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 66 (9) 2725 - 2729 0009-2673 1993/09 [Not refereed][Not invited]
   

  The ferrocene analogue of salicylic acid, 2-hydroxyferrocenecarboxylic acid was synthesized via monolithiation of ferrocene with t-butyllithium, and resolved to optically active forms. Optically active 2-hydroxyferrocene-carboxylic acid was converted to 1-hydroxyferrocenecarbaldehyde, ferrocene analogue of salicylaldehyde, and 2-alkoxyferrocenecarboxylic acids. The later compounds were used as chiral carboxylato ligands for the rhodium(II)-catalyzed asymmetric intramolecular C-H insertion of alpha-diazo beta-keto esters (up to 42% ee).
• SYNTHESIS AND PROPERTIES OF A NEW CHIRAL DIPHOSPHINE LIGAND BEARING A CYCLODEXTRIN-BASED MOLECULAR RECOGNITION SITE AND ITS PALLADIUM(II) COMPLEX

  M SAWAMURA, K KITAYAMA, Y ITO

  TETRAHEDRON-ASYMMETRY 4 (8) 1829 - 1832 0957-4166 1993/08 [Refereed][Not invited]
   

  A new chiral diphosphine tethered to heptakis(2,6-di-O-methyl)-beta-cyclodextrin was synthesized and converted to a water soluble palladium(II) complex. Conductivity and dynamic light scattering measurements and UV-VIS spectra indicated that the palladium complex is aggregated in aqueous solution.
• CATALYTIC ASYMMETRIC-SYNTHESIS WITH TRANSCHELATING CHIRAL DIPHOSPHINE LIGAND TRAP - RHODIUM-CATALYZED ASYMMETRIC MICHAEL ADDITION OF ALPHA-CYANO CARBOXYLATES

  M SAWAMURA, H HAMASHIMA, Y ITO

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 114 (21) 8295 - 8296 0002-7863 1992/10 [Not refereed][Not invited]
  
• CATALYTIC ASYMMETRIC-SYNTHESIS BY MEANS OF SECONDARY INTERACTION BETWEEN CHIRAL LIGANDS AND SUBSTRATES

  M SAWAMURA, Y ITO

  CHEMICAL REVIEWS 92 (5) 857 - 871 0009-2665 1992/07 [Not refereed][Not invited]
  
• CHIRAL PHOSPHINE-LIGANDS MODIFIED BY CROWN ETHERS - AN APPLICATION TO PALLADIUM-CATALYZED ASYMMETRIC ALLYLATION OF BETA-DIKETONES

  M SAWAMURA, H NAGATA, H SAKAMOTO, Y ITO

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 114 (7) 2586 - 2592 0002-7863 1992/03 [Not refereed][Not invited]
   

  Chiral ferrocenylphosphine ligands modified by monoaza or diaza crown ethers of varying ring sizes and linker chain lengths (8a-e, 9) were synthesized. The reaction of the phosphine ligand modified by monoaza-18-crown-6 (8b) and the di-mu-chlorobis(pi-allyl)dipalladium(II) complex in CDC13 produced the pi-allylpalladium(II) complex chelated by the two phosphorus atoms of 8b, leaving the crown ether moiety free. The H-1{H-1} nuclear Overhauser effect study of the pi-allylpalladium(II) complex suggests that the aza crown ether moiety of chiral ligand 8b is located at the proper position to interact with an incoming nucleophile. The palladium catalyst which was prepared in situ by mixing the crown ether-modified chiral ligands and Pd2(dba)3.CHCl3 was examined for stereoselectivity and catalytic activity in the asymmetric allylation of unsymmetrically substituted beta-diketones under solid-liquid, two-phase reaction conditions using potassium fluoride as an insoluble base in mesitylene. The ligands bearing monoaza-18-crown-6 or 1, 10-diaza-18-crown-6 with an appropriate length of linker chain (8b and 8d, respectively) significantly accelerated the allylation and showed fairly high enantioselectivity (up to 75% ee). It is proposed that a ternary complex involving a crown ether, a potassium cation, and an enolate anion attacks a pi-allyipalladium(II) intermediate.
• ASYMMETRIC-SYNTHESIS CATALYZED BY CHIRAL FERROCENYLPHOSPHINE-TRANSITION METAL-COMPLEXES .10. GOLD(I)-CATALYZED ASYMMETRIC ALDOL REACTION OF ISOCYANOACETATE

  T HAYASHI, M SAWAMURA, Y ITO

  TETRAHEDRON 48 (11) 1999 - 2012 0040-4020 1992/03 [Not refereed][Not invited]
   

  Optically active ferrocenylbisphosphine ligands containing 2-(dialkylamino)ethylamino group on the ferrocenylmethyl position have been prepared and used for the gold(I)-catalyzed asymmetric aldol reaction of isocyanoacetate with aldehydes. Six-membered ring amines, such as morpholino or piperidino group, at the terminal of the side chain were most stereoselective to give optically active trans-4-methoxycarbonyl-5-alkyl-2-oxazolines (up to 97% ee) with high enantio- and diastereoselectivity in a quantitative yield.
• SYNTHESIS OF 2,2''-BIS(DIPHENYLPHOSPHINO)-1,1''-BIFERROCENE, A PLANAR CHIRAL BISPHOSPHINE, AND ITS PALLADIUM(II) COMPLEX

  M SAWAMURA, A YAMAUCHI, T TAKEGAWA, Y ITO

  JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS (13) 874 - 875 0022-4936 1991/07 [Not refereed][Not invited]
   

  A new planar chiral bisphosphine, 2,2''-bis(diphenylphosphino)-1,1''-biferrocene (BIFEP), was synthesized via regioselective magnesiation of (diphenylphosphinyl)ferrocene, and converted to its palladium(II) complex.
• SILVER(I)-CATALYZED ASYMMETRIC ALDOL REACTION OF ISOCYANOACETATE

  T HAYASHI, Y UOZUMI, A YAMAZAKI, M SAWAMURA, H HAMASHIMA, Y ITO

  TETRAHEDRON LETTERS 32 (24) 2799 - 2802 0040-4039 1991/06 [Not refereed][Not invited]
   

  High stereoselectivity (over 80% ee) was attained in silver(I)-catalyzed asymmetric aldol reaction of methyl isocyanoacetate with aldehydes in the presence of a chiral (aminoalkyl)ferrocenylphosphine-silver(I) complex by slow addition of the isocyanoacetate over a period of 1 h to a solution of aldehyde and the silver(I) catalyst in 1,2-dichloroethane at 30-degrees-C.
• A TRANS-CHELATING CHIRAL DIPHOSPHINE LIGAND - SYNTHESIS OF 2,2''-BIS[1-(DIPHENYLPHOSPHINO)ETHYL]-1,1''-BIFERROCENE AND ITS COMPLEXES WITH PLATINUM(II) AND PALLADIUM(II)

  M SAWAMURA, H HAMASHIMA, Y ITO

  TETRAHEDRON-ASYMMETRY 2 (7) 593 - 596 0957-4166 1991 [Not refereed][Not invited]
   

  A new chiral diphosphine ligand, (R,R)-(S,S)-2,2''-bis[1-(diphenylphosphino)ethyl]-1,1''-biferrocene, which possesses both central and planar elements of chirality, was synthesized. The NMR studies and molecular weight determination indicated that the ligand chelates to platinum(II) and palladium(II) in trans-manner.
• THE ASYMMETRIC ALDOL REACTION OF TOSYLMETHYL ISOCYANIDE AND ALDEHYDES CATALYZED BY CHIRAL SILVER(I) COMPLEXES

  M SAWAMURA, H HAMASHIMA, Y ITO

  JOURNAL OF ORGANIC CHEMISTRY 55 (24) 5935 - 5936 0022-3263 1990/11 [Not refereed][Not invited]
  
• NMR-STUDIES OF THE GOLD(I)-CATALYZED ASYMMETRIC ALDOL REACTION OF ISOCYANOACETATE

  M SAWAMURA, Y ITO, T HAYASHI

  TETRAHEDRON LETTERS 31 (19) 2723 - 2726 0040-4039 1990 [Not refereed][Not invited]
  
• ASYMMETRIC ALDOL REACTION OF ALPHA-KETOESTERS WITH ISOCYANOACETATE AND ISOCYANOACETAMIDE CATALYZED BY A CHIRAL FERROCENYLPHOSPHINE-GOLD(I) COMPLEX

  Y ITO, M SAWAMURA, H HAMASHIMA, T EMURA, T HAYASHI

  TETRAHEDRON LETTERS 30 (35) 4681 - 4684 0040-4039 1989 [Not refereed][Not invited]
  
• ASYMMETRIC-SYNTHESIS OF (1-AMINOALKYL)PHOSPHONIC ACIDS VIA ASYMMETRIC ALDOL REACTION OF (ISOCYANOMETHYL)PHOSPHONATES CATALYZED BY A CHIRAL FERROCENYLPHOSPHINE-GOLD(I) COMPLEX

  M SAWAMURA, Y ITO, T HAYASHI

  TETRAHEDRON LETTERS 30 (17) 2247 - 2250 0040-4039 1989 [Not refereed][Not invited]
  
• ASYMMETRIC-SYNTHESIS OF BETA-HYDROXY-ALPHA-ALKYLAMINO ACIDS BY ASYMMETRIC ALDOL REACTION OF ALPHA-ISOCYANOCARBOXYLATES CATALYZED BY CHIRAL FERROCENYLPHOSPHINE-GOLD(I) COMPLEXES

  Y ITO, M SAWAMURA, E SHIRAKAWA, K HAYASHIZAKI, T HAYASHI

  TETRAHEDRON 44 (17) 5253 - 5262 0040-4020 1988 [Refereed][Not invited]
  
• ASYMMETRIC-SYNTHESIS OF THREO-SPHINGOSINES AND ERYTHRO-SPHINGOSINES BY ASYMMETRIC ALDOL REACTION OF ALPHA-ISOCYANOACETATE CATALYZED BY A CHIRAL FERROCENYLPHOSPHINE-GOLD(I) COMPLEX

  Y ITO, M SAWAMURA, T HAYASHI

  TETRAHEDRON LETTERS 29 (2) 239 - 240 0040-4039 1988 [Refereed][Not invited]
  
• ASYMMETRIC ALDOL REACTION OF ALPHA-ISOCYANOCARBOXYLATES WITH PARAFORMALDEHYDE CATALYZED BY CHIRAL FERROCENYLPHOSPHINE-GOLD(I) COMPLEXES - CATALYTIC ASYMMETRIC-SYNTHESIS OF ALPHA-ALKYLSERINES

  Y ITO, M SAWAMURA, E SHIRAKAWA, K HAYASHIZAKI, T HAYASHI

  TETRAHEDRON LETTERS 29 (2) 235 - 238 0040-4039 1988 [Refereed][Not invited]
  
• ASYMMETRIC ALDOL REACTION OF ALPHA-ISOCYANOACETAMIDES WITH ALDEHYDES CATALYZED BY A CHIRAL FERROCENYLPHOSPHINE GOLD(I) COMPLEX

  Y ITO, M SAWAMURA, M KOBAYASHI, T HAYASHI

  TETRAHEDRON LETTERS 29 (48) 6321 - 6324 0040-4039 1988 [Refereed][Not invited]
  
• PALLADIUM-CATALYZED ALLYLATION OF ALPHA-ISOCYANOCARBOXYLATES

  Y ITO, M SAWAMURA, M MATSUOKA, Y MATSUMOTO, T HAYASHI

  TETRAHEDRON LETTERS 28 (41) 4849 - 4852 0040-4039 1987 [Refereed][Not invited]
  
• ASYMMETRIC ALDOL REACTION OF AN ISOCYANOACETATE WITH ALDEHYDES CATALYZED BY CHIRAL FERROCENYLPHOSPHINE-GOLD(I) COMPLEXES - DESIGN AND PREPARATION OF NEW EFFICIENT FERROCENYLPHOSPHINE LIGANDS

  Y ITO, M SAWAMURA, T HAYASHI

  TETRAHEDRON LETTERS 28 (49) 6215 - 6218 0040-4039 1987 [Refereed][Not invited]
  
• TRIMETHYLCHLOROSILANE INDUCED RING-OPENING OF 2-ALKYLOXAZOLIDINES TO ENAMINE DERIVATIVES

  Y ITO, M SAWAMURA, K KOMINAMI, T SAEGUSA

  TETRAHEDRON LETTERS 26 (43) 5303 - 5306 0040-4039 1985 [Refereed][Not invited]
  

MISC

• Development of Copper-Catalyzed Highly Selective Organic Reactions

  大宮 寛久, 澤村 正也  化學工業  67-  (5)  361  -366  2016/05
• CATALYTIC ASYMMETRIC ALDOL REACTION - REACTION OF ALDEHYDES WITH ISOCYANOACETATE CATALYZED BY A CHIRAL FERROCENYLPHOSPHINE-GOLD(I) COMPLEX

  Y ITO, M SAWAMURA, T HAYASHI  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY  108-  (20)  6405  -6406  1986/10  [Not refereed][Not invited]
  

Association Memberships

• ロボット合成研究会   コンビナトリアルケミストリー研究会   フラーレン研究会   アメリカ化学会   近畿化学協会   有機合成化学協会   日本化学会   

Research Projects

• Development of Enantioselective Reactions Based on Visible Light Excitation of Chiral Transition Metal Catalysts

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2021/04 -2025/03 

  Author : 澤村 正也, 上野 貢生, 長谷川 淳也
• Development of Boropeptide Chemistry Based on Asymmetric C-H Borylation

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2020/07 -2022/03 

  Author : Sawamura Masaya

   

  An asymmetric C-H boration reaction was attempted using peptide compounds with various structures as reaction substrates, but due to the difficulty in synthesizing the substrate and to the fact that the boration reaction did not proceed as expected, we did not obtain any useful results. Regarding the synthesis of medium molecular peptides containing unnatural amino acids, it was found that the reaction between an alkylboronate and an isocyanate proceeded efficiently under the reaction conditions using a rhodium catalyst. In the palladium-catalyzed reaction of aryl halides, the sterieochemistry of the coupling reaction is reversed depending on whether the reaction substrate is a boronate produced from a secondary amide or a tertiary amide. However, as the above studies proceeded, it gradually became clear that the reproducibility of the C-H boration reaction was not good, resulting in a significant delay in the progress of the research.
• Ligand Design for Catalytic Asymmetric C-H Bond Functinalization

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2018/04 -2022/03 

  Author : Sawamura Masaya

   

  <1. Application of prolinol-phosphine ligands> We developed new reactions and ligands focusing on non-classical hydrogen bonding with sp3-C-H bonds. Furtheremore, copper-catalyzed asymmetric Kinugasa reaction and silver-catalyzed isocyanoacetate asymmetric Aldol reactions were developed. We also clarified the importance of sp3-C-H/π interaction in the study of Ir-catalyzed hydrogen transfer asymmetric reduction of ketones. <2. Application of phenol-carbene ligands> We developed a copper-catalyzed reaction between organic boron and silicon compounds. These studies led to the discovery of a visible light-driven copper-catalyzed asymmetric allyl-position acylation reaction. <3. Pd-catalyzed asymmetric allylation of alkylazaarene> Highly enantioelectivities have been achieved with a cleft-type monodentate diamidophosphite ligand.
• Development of Highly Active Transition Metal Catalysts Based on Solid Support Strategies

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2015/06 -2020/03 

  Author : Sawamura Masaya

   

  Polystyrene(PS)-supported phosphines are widely used for heterogeneous metal catalysis. The phosphine moieties have generally significant mobility even in cross-linked PS resins, and hence exhibit ligand properties similar to those of their homogeneous counterparts. In many cases, however, the polymer chain causes unfavorable steric effects, resulting in reduced catalyst efficiency. We prepared a new type of PS-phosphine hybrid (PS-DPPBz) through radical emulsion copolymerization of styrene monomers in the presence of tetravinylated 1,2-bis(diphenylphosphino)benzene. PS-DPPBz exhibited good swelling properties with aprotic organic solvents. As a conceptual advance of our studies with solid-immobilized ligand toward enantioselective reactions, we showed that the BINOL-based monodentate phosphite chiral ligand enabled the highly enantioselective Ir-catalyzed directed borylation of unactivated methylene C(sp3)-H bonds in saturated hydrocarbon frameworks of substituted heteroarenes.
• シリカ担持配位子をプラットホームとする遷移金属触媒の集積化と有機合成への応用

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2012/04 -2014/03 

  Author : 澤村 正也

   

  かご型ホスフィンSilica-SMAPを用いる触媒反応の開発を進めるとともに、その設計概念を拡張して、遷移金属と１：１型錯体を選択的に形成する新しい固相担持ホスフィンとしてシリカ３脚担持ホスフィンSilica-3p-TPPおよびポリスチレン３点架橋ホスフィンPS-TPPを開発した。これらのホスフィンはSilica-SMAPと比べて、低コストで合成でき、構造の多様化が可能であるなどの利点を有している。塩化アリール類の各種クロスカップリングやsp3-C-H結合のホウ素化反応に対してその有用性を確認した。
• Construction of Medium-Sized Ring Compounds through Molecular Folding

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2011 -2012 

  Author : SAWAMURA Masaya

   

  A cationic gold(I) complex bearing a semihollow-shaped triethynylphosphine ligand efficiently catalyzed cyclizations of various alkynes tethered to different nucleophilic functional groups such as alcohols, sulfonamides, and silyl enol ethers due to an entropy-based rate enhancement. Trityl-based semihollow triethynylphosphines were synthesized and employed as ligands in the gold-catalyzed 8-exo-dig cyclization of acetylene-tethered silyl enol ethers to obtain eight-membered-ring carbocycles.
• シリカ担持配位子をプラットホームとする遷移金属触媒の集積化

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2010 -2011 

  Author : 澤村 正也

   

  固相担持触媒は反応生成物との迅速分離が可能であること、反応空間における位置を規定できることなどから、複数の反応を時間的・空間的に結合させる集積化有機合成に有用である。我々が開発したシリカ担持モノホスフィンSilica-SMAPは、遷移金属種と厳格に1:1の関係で錯形成し、個々の錯体ユニットが空間的に分離される。結果、Silica-SMAP-遷移金属系は高度配位不飽和種を効果的に発生させるのに有用であり、様々な反応に高い触媒活性を示す。本研究では、Silica-SMAPを利用して、異種金属を同一表面に固定化し、第1段階の生成物が第2段階の基質となるドミノ触媒反応を実施することを計画した。 このような計画を実施するための準備研究として、まずSilica-SMAPとRhとの1:1錯体を用いることで、窒素系官能基を配向基とするオルト位選択的芳香族C-Hホウ素化反応を開発した。本反応では、様々な含窒素ヘテロ環官能基の他、イミノ基やsp3窒素を持つ第3級アミノ基などの多様な窒素系官能基が配向基として機能し、立体障害への許容性も優れている。これによって既存の方法では導入困難な位置でのホウ素化が可能となった。配向基の窒素原子がRhに配位して配向基に隣接するC-H基が選択的に活性化されるものと考えられる。 さらに、Silica-SMAPとPd(OAc)2からin-situ調製される触媒が、クロロアレーンとフェニルボロン酸のクロスカップリングに高い活性を示すことを見出した。求電子剤としてクロロアレーンを用いる場合には、配位子として嵩高いものが適しているということがよく知られているが、Silica-SMAPは極めて嵩の小さな配位子であり、この条件を満たさない。シリカ担持していない均一系のSMAP配位子を用いるとまったく触媒活性が得られない。
• Regio-and Stereoselective Transformation of Internal Allylic Systems

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2009 -2011 

  Author : SAWAMURA Masaya

   

  Transition-metal-catalyzed allylic substitution reactions with nucleophiles are among the most important transformation methods in modern organic synthesis because of their broad substrate scope under mild reaction conditions and applicability to enantioselective reactions, as well as the versatility of the alkene functionality adjacent to the chiral center for stereoselective derivatization. However, allylic substitution of unsymmetrically substituted allylic substrates occurs competitively at the α-and γ-positions due to formation of a (π-allyl)metal intermediate : the regioselectivity is highly dependent on the substitution pattern of the allylic substrates. In this research, the principle of catalytic γ-selective substitution of allylic systems has been established, and new organic synthetic reactions have been developed.
• 光学活性ビスシリルシクロプロパンを用いるキラルメソポーラス有機シリカの合成

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2008 -2009 

  Author : 澤村 正也

   

  キラルメソポーラス有機シリカ合成のために必要な1,2-ビスシリルシクロプロパンの合成法を種々検討したが、銅触媒によるγ-ケイ素置換アリルアルコール誘導体とシリルホウ素化合物の反応性が乏しく、有効な反応を開発することができなかった。しかしこの研究の過程で、δ-ケイ素置換ホモアリルアルコール誘導体とジボロン化合物から1-シリル-2-ボリルシクロブタン誘導体を生成する銅触媒新反応を発見した。出発物質の立体化学に応じて、トランス体およびシス体の生成物どちらも、それぞれ選択的に合成することができることが大きな特徴である。このようにシリル化反応によりビスシリルシクロプロパンおよびビススシリルシクロブタンを直接合成することが現段階では困難であるので、ケイ素-ホウ素二官能性化合物のホウ素をケイ素に変換する方法を現在検討中である。 アリルアルコール誘導体のシリル化を検討する中で、シリルホウ素化合物とプロパルギルアルコール誘導体からシリルアレンが生成する反応がロジウム触媒により効率よく進行することを見出した。これは官能基許容性の高いシリルアレンの合成法として有用である。キラルプロパルギルアルコール誘導体の反応は立体特異的に進行し、軸不斉シリルアレンを選択的に与えることも明らかにした。軸不斉シリルアレンはルイス酸存在化アルデヒドと立体選択的に反応し、光学活性ビスプロパルギルアルコール誘導体を効率よく与えることも確認した。今後はこの反応の有機合成への応用を展開する予定である。
• 固体表面のホスフィン精密修飾による協奏機能触媒の開発

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2008 -2009 

  Author : 澤村 正也

   

  Silica-SMAPと[Ir(OMe)(cod)]_2から調製される固定化Ir触媒はジボロン化合物による芳香族C-Hホウ素化反応に活性を示した。ベンゼンなどのように官能基を持たない芳香環も反応するが、配位性官能基(配向基)を持つアレーンは特に高い反応性を示し、オルト位が選択的にホウ素化される。エステル、アミド、アセタール、MOMエーテル、スルホン酸エステル、塩素原子など様々な官能基が配向基として働き、中でもエステルの配向(活性化)効果が最も大きい。またSilica-SMAP-Ir触媒は反応位置が立体的に混み合った多置換基質に対しても優れた適用性を示した。 Silica-SMAP-Ir触媒によるフェノール類のホウ素化を検討し、フェノール性水酸基をカーバメート型に変換することによりオルト位ホウ素化が進行することを見出した。生成物のホウ素部位を炭素-炭素結合形成に利用した後、カーバマート部位を脱離基としてカップリング反応を実行できる。 Silica-SMAP-Ir触媒によるヘテロアレーンのホウ素化を検討し、エステルが優れた配位性配向基となることを明らかにした。ビピリジン型配位子を含むIr錯体を触媒として用いた場合は、ヘテロアレーンの母核ヘテロ原子のα位か最も立体障害の少ない位置でのホウ素化が進行することが報告されているが、これに対しSilica-SMAP-Ir触媒による反応では、エステルに隣接するC-Hが優先的にホウ素化された。チオフェン、ベンゾチオフェン、ベンゾフラン、ピロール、インドール、カルバゾールなど様々なヘテロアレーンに適用することが可能である。
• ホウ素アニオン等価体の触媒的発生法の開発と有機合成への応用

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2007 -2008 

  Author : 澤村 正也

   

  光学活性アリルホウ素化合物は、カルボニル化合物を穏やかな条件で選択的にアリル化し、光学活性ホモアリルアルコールを与える有用な反応剤である。しかし、既存の合成法ではキラル補助基が化学量論量以上必要である上、多段階を要する。また複雑な骨格を持ったものや官能基化したものへの適用が困難である。これらの問題を解決できる汎用性の高い触媒的不斉合成法の開発が望まれる。 我々がすでに開発しているCu(I)-Xantphos触媒によるアリルホウ素生成反応は、入手容易なアリルアルコール誘導体を位置および立体選択的にアリルホウ素化合物に直接変換できる唯一の反応である。Z配置のアリル炭酸エステルの反応に光学活性配位子としてQuinoxP^*を用いることにより、96%eeという実用的レベルの高選択性を達成できた。 当該年度においてはXantphos-銅(I)触媒によるアリルホウ素の合成法を研究する中で、脱離基γ位の置換基がシリル基の場合、Cu-Bのアルケンへの付加の位置選択性が逆転し、trans-1-シリル-2-ボリルシクロプロパンが生成することを見出した。ホスフィン配位子としてXantphosの代わりにSEGPHOSやQuinoxP^*を用いると、高い光学純度のtrans-1-シリル-2-ボリルシクロプロパンが高収率で得られた。 またXantphos-銅(I)触媒をプロパルギルアルコール誘導体とジボロンの反応に適用することによりアレニルホウ素化合物を高収率で得ることにも成功した。
• アルキンへの分子内シラノール付加に基づく立体選択的鎖状炭素骨格構築法の開発

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2007 -2007 

  Author : 澤村 正也

   

  プロパルギルアルコールのシリル化で得られるシラノールの触媒的分子内付加反応によりアルキンをシリルエノールエーテルに変換する方法を検討し、AuCl(PPh_3)/AgOCOCF_3触媒が反応促進に効果的で、Z体が立体選択的に得られることを見出した。本研究では、さらにこれを炭素鎖伸長反応に利用する新規合成手法を確立することを目的として研究を行ったが、好適な条件を見いだすには至らなかった。 本変換反応の出発原料となる光学活性プロパルギルアルコールの合成法として、光学活性銅触媒による末端アルキンのアルデヒドへの付加反応を検討した。その結果、トランスキレート型ビスホスフィン配位子TRAPとCu(O-t-Bu)から調製される錯体が効果的な触媒となることを見いだした。本反応はアルコール溶媒中で円滑に進行し、tert-BuOHなどの嵩高いアルコール中で特に高いエナンチオ選択性が得られた。さらにこの反応の反応機構を知るために、量論反応をNMRで追跡する実験を行い、ビスホスフィンがキレート配位した銅(I)アセチリドが生成すること、および、これがアルデヒドに付加する段階は出発物側に大きく偏った平衡反応であり、過剰のアルキンの存在下でのみ進行することを明らかにすることができた。さらに上記の溶媒効果の結果から、アセチリドのアルキンへの付加の段階は、アルコールが銅に配位するとともに、アルデヒドを分子内水素結合により活性化する6員環遷移状態を経て進行することが強く示唆される。
• シリカ担持かご型トリアルキルホスフィンによる協奏機能触媒の開発

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2007 -2007 

  Author : 澤村 正也

   

  1.シリカ担持かご型ホスフィン[silica]-SMAPに関する研究 シリカゲル表面上にジシロキサン結合を介してSMAP骨格を直接結合させることにより得られるシリカ担持ホスフィン[Silica]-SMAPは、構造的剛直さのため一つの金属中心に対して2つ以上のリン中心で配位することができないことが最大の特徴である。しかもリン原子の周りの立体障害は究極的に小さく、独特の配位空間を形成すると考えられる。本研究では、[Silica]-SMAPと[lrCl(1,5-cyclooctadiene)]]_2から調製される表面固定化Ir錯体が嵩高い多置換アルケンの水素化に非常に高い活性を示すことを見いだした。さらに[Silica]-SMAPと[RhCl(ethylene)_2]]_2から調製される固定化Rh錯体を用いることにより、多置換ベンゼンの水素化にも成功した。 2.アルカンチオール化SMAPの金表面高密度自己組織化と触媒反応への応用に関する研究 まずアルカンチオール化SMAPを合成し、これを用いて金表面上に自己組織化単分子膜を形成させた。表面構造の解析は、XPS,ICP-MS, AFM, CVなどにより行い、表面上でホスフィンがほぼ最密充填していることを明らかにした。そのRh錯体はアルコールの脱水素化に対して高い触媒活性と優れた再利用効率を示した。幅広い一級アルコールに対して室温で高い活性を示す一方、2級アルコールにはまったく活性を示さない点も本触媒系の大きな特徴である。
• Catalyst Design Based on Functionalized Phosphines with a Compact Coordination Center

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2006 -2007 

  Author : SAWAMURA Masaya

   

  1. Research with Caged Phosphine SMAP The procedure for the synthesis of Ph-SMAP, the parent compound for various SMAP derivatives, was improved. It was confirmed that Ph-SMAP is an excellent ligand for hydrosilylation and hydrgenation of ketones. SMAP was immobilized on silica gel surface. Silica-SMAP thus obtained showed very high ligand performance for the Rh-catalyzed hydrosilylation and hydrogenation of sterically demanding ketones.Furthermore, Silica-SMAP was successfully used for the development of Ir-catalyzed directed ortho borylation of functionalized arenes. SMAP derivatives bearing an alkanethiol pendant at the bridgehead silicon atom was prepared and used for the preparation of self-assembled monolayer on gold surface. Au-SMAP thus prepared showed remarkably high activity and turnover efficiency in the Rh-catalyzed dehydrogenative alcohol silylation. 2. Research with Semihollow Trialkynylphosphines Triethynylphosphine ligands with different end-cap groups were synthesized. Those with bulky end-caps showed unique coordination properties to form 1:1 metal-phosphine complexes selectively with various transition metal species. The semihollow-shaped triethynylphosphines showed extraordinally high accelerating effect in the Rh-catalyzed hydrosilylation of ketones. Furthermore, the semihollow triethynylphosphines were successfully used as ligands for gold-catalyzed alkyne cyclizations. In particular, the accelerating effect in the 6-exo-dig and 7-exo-dig cyclization was remarkable. In addition, this catalyst system enabled unprecedented cyclizations of internal alkyne derivatives.
• 11族元素錯体触媒による新反応と不斉反応の開発

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2006 -2006 

  Author : 澤村 正也

   

  我々がすでに開発しているCu(I)-Xantphos触媒によるアリルホウ素生成反応は、アリルアルコール誘導体を位置および立体選択的にアリルホウ素化合物に直接変換できる唯一の反応である。 光学活性配位子を適用してこの反応を不斉触媒化することを検討し、Z配置のアリル炭酸エステルの反応に、不斉配位子として1,2-ビス(ホスフィノ)アレーン骨格を有し、リン原子がジアルキル-モノアリールホスフィン型のものを適用することにより高いエナンチオ選択性が発現することを見出した。不斉配位子としてQuinoxP^*を用いることにより、96%eeという実用的レベルの高選択性を達成できた。 シクロプロパン骨格は天然有機化合物にしばしば見られる構造であるとともに、液晶のコアとしても利用されている。ボリルシクロプロパンはこれらシクロプロパン骨格を持つ化合物を合成するためのビルディングブロックとして有用である。シクロプロパン化合物の多くは環内に不斉点を有するため、光学活性ボリルシクロプロパンは特に重要である。 既存の光学活性ボリルシクロプロパン合成法のほとんどは不斉補助基を量論的に用いるものであり、触媒的不斉合成は、置換シクロプロペンの不斉ヒドロホウ素化によるものが唯一の例である。 Xantphos-銅(I)触媒によるアリルホウ素の合成法を研究する中で、脱離基γ位の置換基がシリル基の場合、Cu-Bのアルケンへの付加の位置選択性が逆転し、その結果としてtrans-1-シリル-2-ボリルシクロプロパンが生成することを見出した。アリル炭酸エステルのアルケン部位の立体配置が、反応性、付加の位置選択性、立体選択性のいずれにも大きな影響を及ぼし、いずれもZ体の方が優れている。ホスフィン配位子としてXantphosの代わりにSEGPHOSやQuinoxP^*を用いると、反応速度が少し低下したが、高い光学純度のtrans-1-シリル-2-ボリルシクロプロパンが高収率で得られた。 シクロプロパン上のシリル基とボリル基は、それぞれ段階的に立体選択的に変換可能である。これを利用する収束的な合成法は、光学活性シクロプロパン化合物の優れた合成手法になるものと期待できる。
• 遷移金属錯体触媒の精密組織化と応用

  ＪＳＴ戦略的創造研究推進制度（個人研究型） （個人研究推進事業：さきがけ研究２１‐ＰＲＥＳＴＯ）

  Date (from‐to) : 2002 -2005
• Atomic Level Organization of Transition Metal Complexes for Use in Organic Synthesis

  JST Basic Research Programs (Precursory Research for Embryonic Science and Technology :PRESTO)

  Date (from‐to) : 2002 -2005
• 炭素クラスター複合体の精密有機合成化学

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2001 -2004 

  Author : 中村 栄一, 松尾 豊, 赤阪 健, 澤村 正也

   

  2002年よりフラーレン,ナノチューブの大量合成が企業化され,ナノテクノロジーの中核技術としてますます注目されている.フラーレンやカーボンナノチューブなどの炭素クラスターそのものの性質は相当程度解明されたといえるが,それらの材料としてのポテンシャルを高めるためには,「化学修飾炭素クラスターの精密合成化学」の研究を展開することが必須である.本研究の目的は,炭素クラスター同士の複合体,炭素クラスターと有機分子,金属,生体分子などとの複合体を,炭素共有結合形成を鍵にして高効率・高選択的に作り出すことである.その結果,次世代の材料科学,ナノテクノロジーや医学に資する新しい物質科学を創成できると同時に,精密合成化学,触媒化学など基礎化学分野での新発見が期待できる. 本年度は,機能性炭素クラスター分子合成の取りまとめとして,五重付加型フラーレン誘導体およびアミノ化フラーレン誘導体の工業製品レベルの大量供給の方法を確立した.また,フラーレン誘導体からさらに修飾して得られるフラーレン-遷移金属錯体についてもいくつか代表的なものについては簡便に大量合成を行う方法を開発した.さらに,官能基化されたフラーレン遷移金属錯体や多核のフラーレン-遷移金属錯体を合成する手法も確立し,今後,電子デバイスへの実用化に向けた研究を展開することが可能となった.新しい分子集合の様式で液晶性を示す炭素クラスター複合体液晶分子(シャトルコック液晶分子)についても,より液晶相を発現させやすく,種々の誘導化が簡便な第二世代のシャトルコック分子を大量合成を可能にする研究を行った。また,金属内包フラーレンイオン種の種々の反応(ケイ素化反応,カルベンとの反応,ジアゾ化合物との反応など)について研究を行い,得られる化合物の反応性と物性を調査した.
• Synthetic Chemistry and Materials Chemistry of Functionalized Fullerenes

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2001 -2002 

  Author : MASAYA Sawamura

   

  During our studies on fullerene functionalization, we have found a one-step five-fold addition of a phenylcopper(I) reagent to [60]fullerene. This reaction produces a.cyclopenadiene embedded in a spherical surface of [60]fullerene. The cyclopentadiene in the new molecule consists of one of the twelve pentagon of [60]fullerene, and is surrounded by the five sp3 carbon atoms bearing a phenyl substituent derived from the organocopper reagent. The cyclopentadiene structure can be converted into 6-π electron cyclopentadienyl anion through deprotonation by a base. Metal complexes containing a five-carbon ligand cyclopentadienyl (Cp) play very important roles in organometallic chemistry. This study aimed at synthesis of functional molecules useful for applications as catalysts and materials by means of such functionalized fullerenes. As results of this study, the multiple addition of organocopper reagents to fullerenes have been significantly improved so that various fullerene derivatives with different organic substituents can be synthesized in quantitative yields in large scales. Hybrids of fullerenes (C60 and C70) and ferrocene were synthesized. It was found that alkali metal salts of the cyclopentadienyl type-fullerenes are soluble in water and that they forms spherical bilayer vesicles. Derivatives with liquid crystalline properties and double decker Cp-type compounds were also synthesized.
• 最小最強ホスフィン配位子―ケイ素含有カゴ型ホスフィンの設計と合成

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2001 -2001 

  Author : 澤村 正也

   

  本研究課題では,これまでに知られるどのホスフィン配位子よりも立体障害が小さく,電子供与性が強い「世界最小・最強ホスフィン配位子」としてケイ素含有カゴ型ホスフィンを設計し,その合成経路に関する検討を徹底的に行った.この配位子はケイ素原子とリン原子の間に効果的な軌道相互作用があり,これによりリン原子の電子供与性が著しく増大することが非経験的分子軌道計算(プロトン化による安定化の比較,HF/3-21G^<(*)>)による検討からすでに明らかになっている.その合成戦略として,ケイ素原子上での環形成により合成を完了する経路とリン原子上での環形成をもって達成する経路を検討した. 前者の経路はまず,トリビニルホスフィンに対するシランの連続ヒドロシリル化により一気にビシクロ骨格を構築することを計画して行った.しかしながら,分子間でのヒドロシリル化や自己重合を抑えられず合成経路としては不向きであることが判明した.また,トリス2-メタロエチルホスフィン-ボラン錯体を合成中間体としてケイ素原子上での環形成を種々試みたが,錯体の安定性等に問題があった. もう一方の経路であるリン原子上での環形成を伴う手法では,トリビニルホスフィンを出発原料とした.トリス(2-ブロモエチル)シランを合成し,これをリチウム-ハロゲン交換によりリチオ化した後に,塩化リンを加えたところ,ESI-マススペクトルにより目的のカゴ型ホスフィンの生成を示唆するピークが得られた.
• キレートホスフィンによる大環状メタラサイクルの構築

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2001 -2001 

  Author : 沢村 正也
• 単一金属系新反応

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1997 -1999 

  Author : 村井 真二, 真島 和志, 直田 健, 澤村 正也, 溝部 裕司, 水野 一彦, 光藤 武明, 村上 正浩, 岩澤 康裕

   

  当初から述べているように、本研究では単一金属系新反応の分野における新概念の開拓と蓄積をはかり、合成化学的応用に結びつけることを目的としている。これらの単一金属としては遷移金属元素や前周期遷移金属元素を主にとりあげ、典型金属元素もとりあげている。 本年度も引き続き、炭素共有結合形成のための新手法の開発を行った。そのため、遷移金属元素を中心として、これらと種々の型式の有機化合物ないし、有機化合物中の官能基との相互作用を極めて広範囲に調査し、これらを通じて得られる異常現象、非古典的現象の芽を蓄積し、専門の異なる研究者がチームをつくりつつ、これらの新現象の普遍化への方策を開拓した。 研究成果の一例として、前年度に導入した高性能な核磁気共鳴吸収装置は、引き続き順調に稼働しており、C-H/オレフィンカップリング反応機構をさらに深く追及していくことができた(村井)。14族有機金属化合物の光誘起電子移動反応の新たな解明にむけての成果が得られた(水野)。また、炭素間単結合間に分子内のオレフィンが挿入するという新触媒反応を見い出した(村上)。 さらに、本年度導入した反応解析モニタリングシステム(React IR 1000)は順調に稼働しており、反応の機構や経路についての重要なデータを鋭意蓄積しつつある(澤村)。 全体として、本年度は計画通り順調に研究が進展したといえる。
• 新有機反応メディア

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1997 -1999 

  Author : 吉田 潤一, 碇屋 隆雄, 大嶋 幸一郎, 神戸 宣明, 谷野 圭持, 岩澤 伸治, 澤村 正也, 堀口 良昭

   

  本研究では新化学現象・新反応の発見と開拓のために、反応の分子環境としての反応場、反応剤、反応媒体、反応手法などを反応メディアという観点から研究を行ってきた。とくに、電子移動反応場、高分子反応場、結晶反応場、ラジカル反応場、金属錯体反応場、特異条件反応場とそれらの境界領域について重点的に検討を行い、新現象・新反応の発見を目指して検討を行ってきた。その結果、多くの特筆すべき成果を得ることができた。以下に示す。 電子移動反応場においては、活性種の生成条件を高度に制御することにより、生成した活性種を蓄え、それを結合生成反応に用いるというカチオンプール法を開拓し、炭素-炭素結合生成反応の新しい方法論を明らかにした。さらに、電解反応場と固体マトリックス反応場の組み合わせにより、高効率・高選択的な分子変換法を明らかにした。また、有機金属反応場、ラジカル反応場、カチオン反応場においては、新活性種や機能性反応場反応の構築などにおいて顕著な成果を上げることができた。 媒体の研究においても注目すべき成果が得られた。すなわち、水中におけるラジカル反応において、従来の有機溶媒中の反応にみられない興味深い応性の変化や選択性の変化が観測されることを明らかにした。また、水中におけるイオン反応の促進効果を利用し、ラジカル反応とイオン反応を組み合わせる新しい反応系の開発をも明らかにした。さらに、超臨界流体における金属触媒反応においては、流体の特性を活かすことにより触媒の活性を大きく向上できることを明らかにした。
• ポルフィリン-遷移金属ホスフィン錯体集積反応場による光エネルギーの利用

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1998 -1998 

  Author : 澤村 正也

   

  ポルフィリンの光機能物質としての性質と遷移金属ホスフィン錯体の多彩な触媒活性を組み合わせることにより,光エネルギーを有効利用できる触媒的物質変換システムを創出することを目的として,ポルフィリン部位を有するビスホスフィン錯体およびその遷移金属錯体を合成した.自然光を利用するアルカンの脱水素反応(不活性C-H結合活性化)を実現することが究極の目標である. (1) 配位子の合成 目的化合物のホスフィン部位は酸化反応に対して不安定と予想されたので,あらかじめホスフィンスルフィドとして保護してからポルフィリン環に組み込み,最終段階で脱保護をする戦略をとった.その結果,リン原子の位置が異なる2種類の配位子を合成することに成功した. (2) 遷移金属錯体の合成と物性 触媒反応の検討に先立ち,いくつかの基本的な遷移金属ホスフィン錯体を合成し,その構造および性質を調べた.吸収スペクトルおよび蛍光スペクトルを測定した. (3) 触媒反応 今回合成された錯体の内,パラジウム錯体は有機ホウ素化合物と有機ハロゲン化物のクロッスカップリングに,ロジウム錯体は活性化ニトリルのマイケル付加に活性を示した.
• Synthesis of Functional Organometallic Complexes Involving a Pentahaptofullerene Ligand

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1997 -1998 

  Author : SAWAMURA Masaya

   

  The pentaphenylated fullerene anion C_<60>Ph_5-, which is obtained through the five-fold addition of an organocopper reagent to C_<60>, and its metal complexes represent a new class of cyclopentadiene derivatives, which can be prepared through deprotonation of the parent compond. One out of twelve pentagons in C_<60> is isolated from the remaining 50 sp^2 carbon atoms of the C_<60> molecule by five surrounding sp3 carbon atoms each bearing a phenyl group. The previous X-ray crystallographic studies revealed the highly unique cavity structure formed around the cyclopentadienyl (Cp) moiety by the five phenyl groups, but failed to give us information on the electronic properties of these unique molecules. In this research project, we have carried out ab-initio molecular orbital calculations and electrochemical experiments and obtained evidence that there is endohedral homoconjugation, that is, an electronic interaction between the upper Cp and the lower C_<50> moiety in C_<60>Ph_5-and C_<60>Ph_5H through inside of the C_<60> cage. We also found that the reaction of C_<70> with an organ ocopper reagent gives a trisaddition product [C_<7O>Ar_3H, Ar = 4-CF_3-C_6H_4] with an indene-like substructure flanked by the three sp^3 carbons in a quantitative yield. The trisadduct was deprotonated with metal alkoxides to form the corresponding metal complexes C_<70>Ar_3M [M=K, Tl]. The results of ab initio molecular orbital calculations and X-ray diffraction study suggested that C_<70>Ar_3- coordinates to the metal as an eta^5-indenylide rather than a eta^3-ligand in C_<7O>Ar_3M.
• 機能性有機金属錯体触媒の創出を指向するC_<5v>対称η^5-フラーレン配位子の開発

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1996 -1996 

  Author : 澤村 正也

   

  金属錯体触媒の分野は今,高活性,高選択性を追求する研究から,機能性触媒の開発へと研究のフロンティアが変わろうとしている.これに応じて,新概念に基づいた触媒設計の必要性が生まれてくる.申請者は,フラーレンの特異な電子構造,適度な大きさ,および三次元的な空間の広がりが機能性配位子を設計する上での基盤として適していると考え,これを目指したフラーレンの化学修飾の研究に着手した.そして様々な検討の結果,有機銅試薬のC_<60>への付加反応において,五つのフェニル基が一つの五員環の廻りを取り囲むように位置選択的に連続付加し,C_S対称のシクロペンタジエン型置換体C_<60>Ph_5Hが定量的な収率で得られることを発見,さらに,LiOtBu,KOtBu,TlOEt及びCuOtBu(PEt_3)によって脱プロトン化することにより対応するシクロペンタジエニル型η_5-フラーレン金属錯体を合成した.中でもタリウム錯体についてはX線結晶構造解析にも成功し,C_5対称の構造を確認した(文献1). フラーレンがその球状表面の5角形の部分でη^5-配位する他に類を見ない特異な構造を有するこれらの金属錯体は,予想される主な特徴として,「幅広い金属に対する強い配位力」,「フラーレン部位の可逆的電子受容能および光励起能」,「50π系ポリオレフィン部位とCp部位との間のフラーレンケージ内部空間を通した電子的相互作用」,および「Cp部位を取り囲む5つの置換基により,Cp環を底とする深いすり鉢状の空間が形成される点」などが挙げられ,機能性配位子として要求される性質を備えている.
• 炭素共有結合形成手法の新機軸

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1996 -1996 

  Author : 村井 真二, 沢村 正也, 藤原 祐三, 中村 栄一, 吉田 潤一, 安田 源

   

  本研究は平成9年度新規設定領域として発足予定の重点領域「有機化学新現象-多元素協同作用に基づく炭素共有結合形成の新機軸-」、領域略称「炭素結合形成」、領域番号283、領域代表者大阪大学工学部教授村井真二、研究期間平成9年度-11年度、についてそのスムーズな開始と進展をはかるための企画、調査、調整を行った。 本重点領域研究「炭素結合形成」は、有機化学の新しい現象を発見・開拓し、これらの展開研究を行うことにより、新しい有機合成手法の開拓、新しい有機化学概念の確立、新しい有機化学理論の構築を目指すものである。この重点領域研究の目標達成への準備として、効果的な研究組織、その運営方法、公募研究と計画研究との調整企画、研究評価法の策定などを行った。公募研究の公募については広報活動に努め、ポスターやインターネットホームページ設定等の手段を用いた結果、期待どうり多数の公募研究課題の応募があった。
• トランスキレート光学活性ホスフィンを用いる触媒的不斉合成

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1996 -1996 

  Author : 澤村 正也

   

  申請者らはこれまでに各種遷移金属に対しトランスの位置にまがたってキレート配位する光学活性2座ホスフィン配位子2,2“-bis[1-(diarylphosphino)enthyl]-1,1"-biferrocene(arylTRAP)および2,2“-bis[1-(dialkylphosphino)enthyl]-1,1"-biferrocene(alkyTRAP)を種々合成し,その触媒的不斉合成への応用を行ってきた. これまでもっぱらロジウム触媒による反応において成果を上げていたが,本年度は新たにパラジウム触媒による反応の開発を手掛けた.さまざまな検討を行った結果,1,6-エン-イン化合物の不斉環化反応(文献1)やRh-Pdバイメタリック触媒形によるα-シアノエステルのアリル化反応などの新規不斉触媒反応(文献2)を開発することができた. また芳香族有機金属試薬とハロゲン化アリールのPd触媒不斉クロスカップリング反応(鈴木カップリング)による軸不斉ビアリール化合物の合成についても検討した.不斉反応という観点からはまだ大きな成果は得られていないが,TRAP配位子が本反応において顕著な加速効果を示すという大変興味深い結果を得た.TRAP配位子がパラジウムにトランスキレートの様式で配位することを考慮に入れると,この事実は反応機構的にも興味深い.今後はさまざまな基質の反応にTRAP配位子を適用し,この加速効果の一般性,有用性を検証しながら鋭意検討を加えることにより,本反応が高次構造有機化合物の合成に役立つ,実践的分子変換法となるよう努力する.
• 新規トランスキレート光学活性ホスフィン配位子の開発

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1995 -1995 

  Author : 澤村 正也

   

  申請者らはこれまでに各種遷移金属に対しトランスの位置にまたがってキレート配位する光学活性2座ホスフィン配位子2,2"-bis[l-(diarylphosphino)ethyl]-l,l"-biferrocene(arylTRAP)および2,2"-bis[l-(dialkylphosphino)ethyl]-l,l"-biferrocene(alkylTRAP)を種々合成し,これらのロジウム錯体が活性化ニトリルの不斉マイケル付加反応,ケトンの不斉ヒドロシリル化反応,オレフィンの不斉水素化反応などにおいて非常に効率的な触媒となることを報告している. 本研究では新しい光学活性トランスキレート配位子としてTRAPの2つのフェロセンの間にケイ素原子が挿入した配位子STRAP及び,光学活性meridional3座配位子となることが予想される配位子としフェロセン間にリン原子が挿入したものの合成を試みた. まずSTRAPと3座ホスフィン配位子の両方の合成中間体となる(R)-(S)-{2-(l-diphenylphos-phino)ethyl-l-tributylstanylferrocene}を(R)-[l-(N,N-dimethylamino)ethylferrocene]から1)ジアステレオ選択的オルトリチオ化,2)スタニル化,及び3)ジフェニルホスフィンによる置換反応を経て合成した.続いてブチルリチウムによるトランスメタル化とジクロロジメチルシランによる補足によりSTRAPを一気に合成することを種々の条件で試みたが未だ成功には至っていない.ジクロロフェニルホスフィンによる補足にも成功していない.このような経過を踏まえ,現在は,先にケイ素原子やリン原子でフェロセンを繋いだ後に,ジメチルアミノ基をジフェニルホスフィノ基などで置換する合成経路を検討中である.
• 酵素類似機能を有する光学活性ホスフィン-遷移金属錯体の分子設計

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1991 -1991 

  Author : 沢村 正也
• 酵素の機能を模倣した不斉遷移金属錯体触媒の分子設計及びそれを用いた触媒的不斉合成

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1990 -1990 

  Author : 沢村 正也
• イソニトリルの特性を活かした遷移金属触媒による触媒的不斉合成

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1988 -1988 

  Author : 沢村 正也
• 機能性有機金属化合物の開発
• Development of Functional Organometallic Compounds

Industrial Property Rights

• 新規なトリアルキルホスフィン誘導体

  特開2004-262782