研究者情報

マスター

アカウント（マスター）

• 氏名

  澤村　正也(サワムラ　マサヤ), サワムラ　マサヤ

所属（マスター）

• 理学研究院　化学部門　有機・生命化学分野

所属（マスター）

• 理学研究院　化学部門　有機・生命化学分野

独自項目

syllabus

• 2021, 化学特別講義, Advanced Chemistry, 修士課程, 総合化学院, Organometallics, Organic Chemistry, Nickel Catalysis, Carbocycles, Industrial Chemistry
• 2021, 大学院共通授業科目（一般科目）：自然科学・応用科学, Inter-Graduate School Classes(General Subject):Natural and Applied Sciences, 修士課程, 大学院共通科目, Organometallics, Organic Chemistry, Nickel Catalysis, Carbocycles, Industrial Chemistry
• 2021, 分子化学Ａ（有機金属化学), Molecular Chemistry A (Organometallic Chemistry), 修士課程, 総合化学院, 有機金属化学　有機合成触媒　反応設計　有機金属反応機構　有機金属錯体の構造　有機合成化学　触媒化学
• 2021, 先端総合化学特論Ⅱ, Modern Trends in Chemical Sciences and Engineering II, 博士後期課程, 総合化学院, Organometallics, Organic Chemistry, Nickel Catalysis, Carbocycles, Industrial Chemistry
• 2021, 有機化学Ⅰ, Organic Chemistry Ⅰ, 学士課程, 理学部, 反応、合成、付加反応、置換反応、脱離反応、酸性度

PositionHistory

• 環境保全センター長, 2005年4月1日, 2007年3月31日
• 環境保全センター長, 2007年4月1日, 2009年3月31日
• 環境保全センター長, 2009年4月1日, 2011年3月31日
• 安全衛生本部副本部長, 2013年4月1日, 2015年3月31日
• 安全衛生本部副本部長, 2015年4月1日, 2017年3月31日
• 安全衛生本部副本部長, 2017年4月1日, 2019年3月31日
• 安全衛生本部副本部長, 2019年4月1日, 2021年3月31日
• 安全衛生本部副本部長, 2021年4月1日, 2023年3月31日

researchmap

プロフィール情報

学位

• 京都大学工学博士（京都大学）

プロフィール情報

• 姓

  澤村, サワムラ

• 名

  正也, マサヤ

• ID各種

  200901098220100993

対象リソース

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

業績リスト

研究キーワード

• 有機金属化学   Organometallic Chemistry   

研究分野

• ナノテク・材料 / 有機合成化学
• ライフサイエンス / 生物有機化学
• ナノテク・材料 / 構造有機化学、物理有機化学

経歴

• 2001年 - 現在 - 北海道大学 教授
• 2001年 - 現在 - Hokkaido University Professor
• 2019年 - 2023年 北海道大学 化学反応創成研究拠点(WPI-ICReDD) 教授
• 2016年04月 - 2022年03月 北海道大学 ディスティングイッシュトプロフェッサー
• 1997年 - 2001年 東京大学 助教授
• 1997年 - 2001年 東京大学
• 1996年 - 1997年 東京大学 講師
• 1996年 - 1997年 東京大学
• 1995年 - 1996年 東京大学 助手
• 1995年 - 1996年 The University of Tokyo, Research Assistant
• 1995年 - 1995年 - 東京工業大学 助手
• 1995年 - 1995年 - Tokyo Institute of Technology, Research Assistant
• 1989年 - 1995年 京都大学 助手
• 1989年 - 1995年 Kyoto University, Research Assistant

学歴

•         - 1989年   京都大学   工学研究科   合成化学
•         - 1989年   京都大学
•         - 1984年   京都大学   工学部   合成化学科
•         - 1984年   京都大学

受賞

• 2022年05月 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年04月 文部科学省 文部科学大臣表彰 科学技術賞 研究部門
   遷移金属有機合成触媒の設計と不斉制御の研究 

  受賞者: 澤村正也
• 2020年02月 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年02月 有機合成化学協会 有機合成化学協会賞
   炭素ー炭素結合形成不斉銅触媒反応の開発 

  受賞者: 澤村 正也
• 2018年03月 根岸賞
   

  受賞者: 澤村 正也
• 2017年01月 名古屋シルバーメダル
   

  受賞者: 澤村 正也
• 2015年02月 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年03月 北海道大学研究総長賞
   

  受賞者: 澤村 正也
• 2012年03月 日本化学会学術賞
   

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

論文

• 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 2024年09月26日 

  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 2024年06月19日
• 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 2024年05月15日 

  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 2024年03月28日 

  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年 

  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年
• 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年10月02日 

  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 2023年08月21日
• 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 2023年08月09日 

  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 2023年07月20日
• Visible-Light-Induced Aminochlorination of Alkenes

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

  Organic Letters 2023年06月08日
• Direct α-Trifluoromethylthiolation of Carboxylic Acids Enabled by Boron Catalysis

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

  Synlett 2023年04月11日 [査読有り][招待有り]
   

  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年 

  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 2022年12月15日 [査読有り][招待有り]
  
• 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 2022年10月18日 [査読有り]
  
• 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年09月20日 [査読有り][招待有り]
  
• 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 2022年07月19日 [査読有り]
  
• 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 2022年07月15日 [査読有り]
  
• 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 2022年06月07日 [査読有り]
  
• 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 2022年01月06日 [査読有り][通常論文]
  
• Visible Light-Induced Reductive Allylation of Aldehydes by Umpolung Approach

  Ibuki Tanaka, Masaya Sawamura, Yohei Shimizu

  Organic Letters 24 2 520 - 524 2021年12月 [査読有り][通常論文]
  
• 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 2021年10月19日 [査読有り]
   

  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 2021年09月09日 

  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年09月09日
• 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 2021年09月09日 [査読有り][招待有り]
   

  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 2021年08月06日 [査読有り][通常論文]
  
• Construction of Medium-Sized Rings by Gold Catalysis

  Ronald L. Reyes, Tomohiro Iwai, Masaya Sawamura

  Chemical Reviews 121 14 8926 - 8947 2021年07月28日 [査読有り][招待有り]
  
• 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 2021年06月05日 [査読有り][通常論文]
  
• Nickel-Catalyzed Homocoupling of Aryl Ethers with Magnesium Anthracene Reductant

  Kosuke Higashida, Masaya Sawamura, Vishal Kumar Rawat

  Synthesis 2021年05月17日 [査読有り][招待有り]
   

  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 2021年05月13日 [査読有り][招待有り]
   

  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 2021年03月16日 [査読有り][通常論文]
  
• 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 2021年03月08日 [査読有り][通常論文]
  
• 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 2021年02月17日 [査読有り][通常論文]
  
• 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 2021年02月 [査読有り][通常論文]
   

  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 2021年01月15日 [査読有り][招待有り]
  
• 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年
• 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 2020年12月18日 [査読有り][通常論文]
  
• 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 2020年10月01日 [査読有り][通常論文]
   

  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 2019年09月20日 [査読有り][通常論文]
  
• 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 2019年08月02日 [査読有り][通常論文]
   

  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 2019年07月17日 [査読有り][通常論文]
   

  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 2019年05月14日 [査読有り][通常論文]
   

  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 2019年05月 [査読有り]
  
• 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 2019年04月 [査読有り][通常論文]
   

  © 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 2019年03月15日 [査読有り][通常論文]
  
• 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 2019年02月01日 [査読有り][通常論文]
  
• 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 2018年09月 [査読有り][通常論文]
  
• 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 2018年07月20日 [査読有り][通常論文]
   

  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 2018年06月25日 [査読有り][通常論文]
   

  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 2018年06月01日 [査読有り][通常論文]
   

  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 2018年02月15日 [査読有り][通常論文]
   

  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 2018年 [査読有り][通常論文]
   

  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 2018年 [査読有り][通常論文]
  
• 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 2018年 [査読有り][通常論文]
   

  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 2018年 [査読有り][通常論文]
   

  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 2018年 [査読有り][通常論文]
   

  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

  Ayaka Yamazaki, Kazunori Nagao, Tomohiro Iwai, Hirohisa Ohmiya, Masaya Sawamura

  Angewandte Chemie International Edition 57 12 3196 - 3199 Wiley-Blackwell 2018年 [査読有り][通常論文]
  
• 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 2017年12月 [査読有り][通常論文]
   

  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 2017年08月 [査読有り][通常論文]
   

  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 2017年06月 [査読有り][通常論文]
   

  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 2017年06月 [査読有り][通常論文]
   

  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 2017年03月 [査読有り][通常論文]
   

  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 α-Quaternary Formimides and Aldehydes through Umpolung Asymmetric Copper Catalysis with Isocyanides

  Kentaro Hojoh, Hirohisa Ohmiya, Masaya Sawamura

  Journal of the American Chemical Society 139 6 2184 - 2187 American Chemical Society ({ACS}) 2017年02月 [査読有り][通常論文]
   

  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 2016年12月 [査読有り][通常論文]
   

  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 2016年08月 [査読有り][通常論文]
   

  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 2016年05月 [査読有り][通常論文]
   

  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 2016年04月 [査読有り][通常論文]
   

  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 2016年 [査読有り][通常論文]
  
• Copper-catalyzed semihydrogenation of internal alkynes with molecular hydrogen

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

  Organometallics 35 10 1354 - 1357 2016年 [査読有り][通常論文]
  
• 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 2015年12月 [査読有り][通常論文]
   

  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 2015年12月 [査読有り][通常論文]
   

  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 2015年09月 [査読有り][通常論文]
   

  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 2015年 [査読有り][通常論文]
  
• Copper(I)-catalyzed intramolecular hydroalkoxylation of unactivated alkenes

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

  Organic Letters 17 9 2039 - 2041 2015年 [査読有り][通常論文]
  
• 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 2015年 [査読有り][通常論文]
  
• 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 2015年 [査読有り][通常論文]
  
• 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 2015年 [査読有り][通常論文]
  
• 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 2015年 [査読有り][通常論文]
  
• Copper-Catalyzed Allylic Substitution and Conjugate Addition with Alkylboranes

  Hirohisa Ohmiya, Masaya Sawamura

  JOURNAL OF SYNTHETIC ORGANIC CHEMISTRY JAPAN 72 11 1207 - 1217 2014年11月 [査読有り][通常論文]
   

  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 2014年11月 [査読有り][通常論文]
   

  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 2014年10月 [査読有り][通常論文]
   

  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 2014年10月 [査読有り][通常論文]
   

  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 2014年10月 [査読有り][通常論文]
   

  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 2014年05月 [査読有り][通常論文]
   

  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 2014年05月 [査読有り][通常論文]
   

  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 2014年05月 [査読有り][通常論文]
   

  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年03月31日 [査読有り][通常論文]
  
• 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 2014年02月 [査読有り][通常論文]
   

  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 2014年01月 [査読有り][通常論文]
   

  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 2014年 [査読有り][通常論文]
   

  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 2014年 [査読有り][通常論文]
  
• 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 2013年11月 [査読有り][通常論文]
  
• 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 2013年10月 [査読有り][通常論文]
  
• 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 2013年09月 [査読有り][通常論文]
   

  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 2013年06月 [査読有り][通常論文]
   

  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 2013年03月 [査読有り][通常論文]
   

  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 2013年02月 [査読有り][通常論文]
   

  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 2013年 [査読有り][通常論文]
  
• 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 2013年 [査読有り][通常論文]
  
• 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 2012年12月 [査読有り][通常論文]
   

  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 2012年11月 [査読有り][通常論文]
   

  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 2012年11月 [査読有り][通常論文]
  
• 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 2012年11月 [査読有り][通常論文]
   

  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 2012年08月 [査読有り][通常論文]
   

  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 2012年07月 [査読有り][通常論文]
   

  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 2012年05月 [査読有り][通常論文]
   

  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 2012年05月 [査読有り][通常論文]
   

  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 2012年05月 [査読有り][通常論文]
   

  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 2012年04月 [査読有り][通常論文]
   

  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 2012年03月 [査読有り][通常論文]
   

  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 2012年02月 [査読有り][通常論文]
   

  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 2012年 [査読有り][通常論文]
  
• 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 2011年12月 [査読有り][通常論文]
   

  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 2011年12月 [査読有り][通常論文]
   

  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 2011年09月 [査読有り][通常論文]
   

  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 2011年09月 [査読有り][通常論文]
   

  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 2011年07月 [査読有り][通常論文]
   

  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 2011年04月 [査読有り][通常論文]
   

  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 2011年03月 [査読有り][通常論文]
   

  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 2011年02月 [査読有り][通常論文]
  
• 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 2011年02月 [査読有り][通常論文]
   

  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 2011年 [査読有り][通常論文]
  
• 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年 [査読有り][通常論文]
  
• Direct enantio-convergent transformation of racemic substrates without racemization or symmetrization

  Hajime Ito, Shun Kunii, Masaya Sawamura

  NATURE CHEMISTRY 2 11 972 - 976 2010年11月 [査読有り][通常論文]
   

  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 2010年10月 [査読有り][通常論文]
   

  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 2010年09月 [査読有り][通常論文]
   

  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 2010年09月 [査読有り][通常論文]
   

  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 2010年08月 [査読有り][通常論文]
   

  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 2010年08月 [査読有り][通常論文]
   

  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 2010年06月 [査読有り][通常論文]
   

  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 - + 2010年05月 [査読有り][通常論文]
   

  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 2010年05月 [査読有り][通常論文]
   

  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 2010年04月 [査読有り][通常論文]
   

  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 - + 2010年03月 [査読有り][通常論文]
   

  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 2010年03月 [査読有り][通常論文]
  
• 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 - + 2010年02月 [査読有り][通常論文]
   

  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 2010年01月 [査読有り][通常論文]
   

  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 2010年 [査読有り][通常論文]
  
• 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 2009年12月 [査読有り][通常論文]
   

  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

  Sawamura Masaya

  有機合成化学協会誌 67 11 1125 - 1135 The Society of Synthetic Organic Chemistry, Japan 2009年11月 [査読有り][招待有り]
   

  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 2009年08月 [査読有り][通常論文]
   

  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 2009年05月 [査読有り][通常論文]
   

  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 - + 2009年04月 [査読有り][通常論文]
   

  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 2009年 [査読有り][通常論文]
   

  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 2008年12月 [査読有り][通常論文]
   

  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 - + 2008年12月 [査読有り][通常論文]
   

  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 - + 2008年11月 [査読有り][通常論文]
   

  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 2008年11月 [査読有り][通常論文]
   

  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 2008年11月 [査読有り][通常論文]
   

  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 2008年11月 [査読有り][通常論文]
   

  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 2008年10月 [査読有り][通常論文]
   

  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 2008年09月 [査読有り][通常論文]
   

  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 - + 2008年08月 [査読有り][通常論文]
   

  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 2008年07月 [査読有り][通常論文]
   

  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 2008年05月 [査読有り][通常論文]
   

  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 2008年 [査読有り][通常論文]
  
• 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 2008年 [査読有り][通常論文]
  
• 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 - + 2007年12月 [査読有り][通常論文]
   

  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 2007年11月 [査読有り][通常論文]
   

  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 2007年10月 [査読有り][通常論文]
   

  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 2007年09月 [査読有り][通常論文]
   

  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 2007年07月 [査読有り][通常論文]
   

  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 2007年 [査読有り][通常論文]
   

  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 2007年 [査読有り][通常論文]
  
• 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 2007年 [査読有り][通常論文]
   

  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 金属電極間に架橋した1,4-二置換ベンゼン単分子の電気伝導度の置換基依存性(ナノチューブ・ナノワイヤ,領域9,表面・界面,結晶成長)

  三浦 進一, 木口 学, 原 賢二, 澤村 正也, 村越 敬

  日本物理学会講演概要集 62.1.4 918  一般社団法人 日本物理学会 2007年
• 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 2007年 [査読有り][通常論文]
   

  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 2006年12月 [査読有り][通常論文]
  
• 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 2006年11月 [査読有り][通常論文]
   

  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 2006年11月 [査読有り][通常論文]
   

  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 2006年09月 [査読有り][通常論文]
   

  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 2006年08月 [査読有り][通常論文]
   

  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 2006年03月 [査読有り][通常論文]
   

  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 2006年 [査読有り][通常論文]
   

  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 金電極に架橋した単一1,4-ジイソシアノベンゼン分子の電気伝導度測定(26pYH ナノチューブ・ナノワイヤ,領域9(表面・界面,結晶成長))

  三浦 進一, 木口 学, 原 賢二, 澤村 正也, 村越 敬, 伊藤 肇

  日本物理学会講演概要集 61.2.4 776  一般社団法人 日本物理学会 2006年
• 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 2005年12月 [査読有り][通常論文]
   

  [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 2005年11月 [査読有り][通常論文]
  
• 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 2005年07月 [査読有り][通常論文]
   

  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 2005年04月 [査読有り][通常論文]
   

  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 2004年07月 [査読有り][通常論文]
   

  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 2004年07月 [査読無し][通常論文]
   

  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 2004年07月 [査読有り][通常論文]
   

  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 2004年06月 [査読有り][通常論文]
   

  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 Complex of ŋ⁵-Cyclopentadienide C₆₀R₅ Ligands. Kinetic and Thermodynamic Stabilization Effects of C₆₀Ph₅ Ligand.

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

  Organometallics 23 13 3259 - 3266 2004年06月 [査読無し][通常論文]
   

  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 2003年07月 [査読有り][通常論文]
   

  [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 2003年03月 [査読有り][通常論文]
  
• Regioselective Synthesis of [60]Fullerene η⁵-Indenide R₃C₆₀-and η⁵ Cyclopentadienide R₅C₆₀-Bearing Different R Groups.

  TOGANOH M, SUZUKI K, UDAGAWA R, HIRAI A, SAWAMURA M, NAKAMURA E

  Org. Biomol.Chem. 1 14 2604 - 2611 2003年 [査読有り][通常論文]
   

  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 2002年10月 [査読有り][通常論文]
   

  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 2002年08月 [査読無し][通常論文]
  
• 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 2002年06月 [査読有り][通常論文]
   

  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 2002年06月 [査読無し][通常論文]
   

  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 2002年 [査読有り][通常論文]
   

  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 2001年07月 [査読無し][通常論文]
   

  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 2001年03月 [査読有り][通常論文]
   

  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 2001年02月 [査読有り][通常論文]
   

  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 2000年12月 [査読有り][通常論文]
  
• Catalytic Asymmetric Hydrogenation of α-Acetamidoacrylates Using TRAP Trans-Chelating Chiral Diphosphine Ligands : Remarkable Effects of Ligand P-substituent and Hydrogen Pressure on Enantioselectivity

  KUWANO R, SAWAMURA M, ITO Y

  Bulletin of the Chemical Society of Japan 73 11 2571 - 2578 2000年11月 [査読有り][通常論文]
   

  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 2000年11月 [査読無し][通常論文]
   

  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 2000年09月 [査読有り][通常論文]
   

  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 2000年06月 [査読有り][通常論文]
   

  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 2000年04月 [査読有り][通常論文]
   

  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 2000年03月 [査読有り][通常論文]
  
• 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 2000年03月 [査読有り][通常論文]
   

  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 2000年02月 [査読有り][通常論文]
   

  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 2000年 [査読有り][通常論文]
   

  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 - + 2000年 [査読有り][通常論文]
  
• 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 1999年 [査読有り][通常論文]
   

  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 π-Indenyl-type Fullerene Ligand and Its Matal Complexes via Quantative Trisarylation of C70

  SAWAMURA M, IIKURA H, HIRAI A, NAKAMURA E

  Journal of the American Chemical Society 120 32 8285 - 8286 1998年08月 [査読有り][通常論文]
  
• 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 1997年11月 [査読有り][通常論文]
  
• 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 1997年11月 [査読有り][通常論文]
   

  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 - & 1997年07月 [査読有り][通常論文]
   

  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 1997年07月 [査読有り][通常論文]
   

  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年 [査読有り][通常論文]
  
• 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 1997年 [査読有り][通常論文]
   

  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 1996年12月 [査読有り][通常論文]
   

  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 1996年12月 [査読有り][通常論文]
  
• 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 1996年08月 [査読有り][通常論文]
  
• 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 1996年08月 [査読有り][通常論文]
   

  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 1996年04月 [査読有り][通常論文]
  
• 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 1996年04月 [査読有り][通常論文]
  
• 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 1996年04月01日 [査読有り][通常論文]
  
• 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 1995年10月 [査読有り][通常論文]
   

  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 1995年10月 [査読有り][通常論文]
   

  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 β-Disubstituted α-Acetamidoacrylates Catalyzed by Rhodium Complexes with TRAP Trans-Chelating Chiral Phosphine Ligands

  SAWAMURA M, KUWANO R, ITO Y

  Journal of the American Chemical Society 117 37 9602 - 9603 1995年09月 [査読有り][通常論文]
  
• Asymmetric Michael Reaction of an α-Cyano Weinreb Amide Catalyzed by a Rhodium Complex with Trans-Chelating Chiral Diphosphine PhTRAP

  SAWAMURA M, HAMASHIMA H, SHINOTO H, ITO Y

  Tetrahedron Letters 36 36 6479 - 6482 1995年09月 [査読有り][通常論文]
   

  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 1995年08月 [査読有り][通常論文]
   

  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 1995年07月 [査読有り][通常論文]
   

  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 1995年04月 [査読有り][通常論文]
   

  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-α-isocyanoacetamide(α-lsocyano Weinreb Amide). An Efficient Synthesis of Optically Active β-Hydroxy α-Amino Aldehydes and Ketones

  SAWAMURA M, NAKAYAMA Y, KATO T, ITO Y

  The Journal of Organic Chemistry 60 6 1727 - 1732 1995年03月 [査読有り][通常論文]
   

  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 α-Cyano Carboxylates Catalyzed by a Rhodium Complex with Trans-Chelating Chiral Diposphire PhTRAP

  SAWAMURA M, HAMASHIMA H, ITO Y

  Tetrahedron 50 15 4439 - 4454 1994年04月 [査読無し][通常論文]
   

  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 1994年01月 [査読有り][通常論文]
  
• 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 1994年 [査読無し][通常論文]
  
• Synthesis of Optically Active Ferrocene Analogues Salicylic Acid Derivatives and Rhodium(Ⅱ)-Catalyzed Asymmetric Intramolecular C-H Insertion of α-Diazo β-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 1993年09月 [査読無し][通常論文]
   

  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 1993年08月 [査読有り][通常論文]
   

  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 Asmmetric Synthesis with Trans-Chelating Chiral Diphosphine Ligand TRAP : Rhodium-Catalyzed Asymmetric Michael Addition of α-Cyanocarboxylates

  SAWAMURA M, HAMASHIMA H, ITO Y

  Journal of the American Chemical Society 114 21 8295 - 8296 1992年10月 [査読無し][通常論文]
  
• CATALYTIC ASYMMETRIC-SYNTHESIS BY MEANS OF SECONDARY INTERACTION BETWEEN CHIRAL LIGANDS AND SUBSTRATES

  M SAWAMURA, Y ITO

  CHEMICAL REVIEWS 92 5 857 - 871 1992年07月 [査読無し][通常論文]
  
• Chiral Phosphine Ligands Functionalized by Crown Ethers : An Application to Palladium-Catalyzed Asymmetric Allylation of β-Diketones

  SAWAMURA M, NAGATA H, SAKAMOTO H, ITO Y

  The Journal of the American Chemical Society 114 7 2586 - 2592 1992年03月 [査読無し][通常論文]
   

  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 1992年03月 [査読無し][通常論文]
   

  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(diphenyl phosphino)-1,1"-biferrocene, a Planar Chiral Bisphosphine, and its Palladium(Ⅱ) Complex

  SAWAMURA M, YAMAUCHI A, TAKEGAWA T, ITO Y

  The Journal of the Chemical Society, Chemical Communications 13 874 - 875 1991年07月 [査読無し][通常論文]
   

  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 1991年06月 [査読無し][通常論文]
   

  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 : 2,2"-Bis[1-(diphenylphosphino)ethyl]-1, 1"-biferrocene and its Complexes with Platinum(Ⅱ)and Palladium(Ⅱ)

  SAWAMURA M, HAMASHIMA H, ITO Y

  Tetrahedron : Asymmetry 2 7 593 - 596 1991年 [査読無し][通常論文]
   

  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 1990年11月 [査読無し][通常論文]
  
• NMR-STUDIES OF THE GOLD(I)-CATALYZED ASYMMETRIC ALDOL REACTION OF ISOCYANOACETATE

  M SAWAMURA, Y ITO, T HAYASHI

  TETRAHEDRON LETTERS 31 19 2723 - 2726 1990年 [査読無し][通常論文]
  
• Asymmetric Aldol Reaction of β-Ketoesters with Isocyanoacetate and Isocyanoacetamide Catalyzed by a Chival Ferrocenylphosphine-Gold(I) Complex

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

  Tetrahedron Letters 30 35 4681 - 4684 1989年 [査読無し][通常論文]
  
• 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 1989年 [査読無し][通常論文]
  
• 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 1988年 [査読有り][通常論文]
  
• 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 1988年 [査読有り][通常論文]
  
• 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 1988年 [査読有り][通常論文]
  
• 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 1988年 [査読有り][通常論文]
  
• PALLADIUM-CATALYZED ALLYLATION OF ALPHA-ISOCYANOCARBOXYLATES

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

  TETRAHEDRON LETTERS 28 41 4849 - 4852 1987年 [査読有り][通常論文]
  
• 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 1987年 [査読有り][通常論文]
  
• TRIMETHYLCHLOROSILANE INDUCED RING-OPENING OF 2-ALKYLOXAZOLIDINES TO ENAMINE DERIVATIVES

  Y ITO, M SAWAMURA, K KOMINAMI, T SAEGUSA

  TETRAHEDRON LETTERS 26 43 5303 - 5306 1985年 [査読有り][通常論文]
  

MISC

• 銅触媒の機能化に基づく高選択的合成反応の開発 (特集 戦略的触媒開発と応用)

  大宮 寛久, 澤村 正也 化學工業 67 (5) 361 -366 2016年05月
• 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年10月 [査読無し][通常論文]
  

所属学協会

• 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   

共同研究・競争的資金等の研究課題

• キラル遷移金属錯体触媒の可視光励起に基づく不斉合成反応の開発

  日本学術振興会：科学研究費助成事業

  研究期間 : 2021年04月 -2025年03月 

  代表者 : 澤村 正也, 上野 貢生, 長谷川 淳也
• 不斉C-Hホウ素化を基盤とするボロペプチド化学の開拓

  日本学術振興会：科学研究費助成事業

  研究期間 : 2020年07月 -2022年03月 

  代表者 : 澤村 正也

   

  ペプチド化合物を反応基質として、不斉C-Hホウ素化反応を試みるたが、基質の合成が困難であったり、想定のホウ素化反応が進行しなかったりしたために、当初期待した成果を得ることはできなかった。含非天然アミノ酸中分子ペプチドの合成に関しては、ある種のアルキルボロネートとイソシアネートの反応が、ロジウム触媒条件で進行することが認められた。パラジウム触媒によるハロゲン化アリールの反応では、反応基質が基質の構造によってカップリング反応の立体化学が逆転するという興味深い現象が見出された。ただし、以上の検討を進めている中、C-Hホウ素化反応の再現性が得られにくくなり、研究の進捗が大幅に遅れた。
• 配位子設計を基盤とするC-H結合不斉変換反応の開発

  日本学術振興会：科学研究費助成事業

  研究期間 : 2018年04月 -2022年03月 

  代表者 : 澤村 正也

   

  〈１. プロリノールーホスフィンの応用〉では、sp3-C-H結合による非古典的水素結合に焦点を当てた反応と配位子の開発を進め、銅触媒不斉衣笠反応や銀触媒イソシアノ酢酸類の不斉アルドール反応を開発した。また、Ir触媒によるケトンの水素移動型不斉還元の研究においてsp3-C-H/π相互作用の重要性を明らかにした。 〈２. フェノール-カルベン配位子の応用〉では、銅触媒による有機ホウ素・ケイ素化合物の反応を開発するとともに、可視光駆動型銅触媒不斉アリル位アシル化反応を見出した。 〈３.アルキルアザアレーンのPd触媒C-H不斉アリル化〉では、クレフト型単座配位子による高選択的反応を開発した。
• 固相担持法による高活性遷移金属錯体触媒の創製

  日本学術振興会：科学研究費助成事業

  研究期間 : 2015年06月 -2020年03月 

  代表者 : 澤村 正也

   

  分離・再利用が容易な高分子固定化金属触媒による合成プロセスの効率化が期待される。しかし、高分子鎖の立体障害に起因する触媒活性の低下がしばしば問題となる。我々は、複数の重合部位を有するホスフィンを高分子架橋剤とすることで金属配位点を空間的に孤立化させて高活性金属種を生成する手法を開発した。単座ホスフィンを３点架橋剤として得られるPS-TPPや２座ホスフィンを４点架橋剤とするPS-DPPBzが代表例である。さらに配位子の空間的孤立化の概念を不斉配位子の開発に展開させて均一系キラルモノホスファイト配位子を設計し、IrおよびRh触媒による不活性C(sp3)-H結合の不斉ホウ素化反応に応用した。
• 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

  研究期間 : 2012年04月 -2014年03月 

  代表者 : 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。
• 小分子フォールディングによる中員環合成

  日本学術振興会：科学研究費助成事業

  研究期間 : 2011年 -2012年 

  代表者 : 澤村 正也

   

  キャビティー状のホスフィン配位子-金錯体触媒を様々なアルキン環化反応に適用し、分子フォールディングによる反応点近接効果に基づく、効率的な環状化合物の合成に成功した。従来型よりも深く狭いキャビティーを持つトリチル置換基を有する新規ホスフィン配位子を設計・合成し、アルキニルシリルエノールエーテルの金触媒環化反応が効率良く進行し、8員環カルボサイクルが得られることを見出した。
• 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

  研究期間 : 2010年 -2011年 

  代表者 : 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。
• 内部アリル系の位置および立体選択的変換反応

  日本学術振興会：科学研究費助成事業

  研究期間 : 2009年 -2011年 

  代表者 : 澤村 正也

   

  遷移金属触媒によるアリル系化合物の活性化を経る炭素.炭素および炭素.ヘテロ元素結合形成反応は汎用性の高い有用な有機合成手段である。しかし、アリル系両端に立体的および電子的に似た置換基を持つ化合物(内部アリル系)の反応では位置選択性の制御が困難であり、この手法の適用範囲を著しく制限している。本研究は、独自の反応設計原理に基づく新規触媒反応の開発によってこの問題を解決し、新しい有機合成の発展に寄与した。
• 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

  研究期間 : 2008年 -2009年 

  代表者 : 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

  研究期間 : 2008年 -2009年 

  代表者 : 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

  研究期間 : 2007年 -2008年 

  代表者 : 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

  研究期間 : 2007年 -2007年 

  代表者 : 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

  研究期間 : 2007年 -2007年 

  代表者 : 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。
• コンパクトな配位中心を持つ官能性ホスフィンを基盤とする触媒設計

  日本学術振興会：科学研究費助成事業

  研究期間 : 2006年 -2007年 

  代表者 : 澤村 正也

   

  1.かご型ホスフィンSMAPに関する研究 かご型ホスフィンSMAPの親化合物であるPh-SMAPの合成法の改良を検討し、単工程、高収率で合成する方法を開発した。また、その遷移金属錯体の合成、X線結晶構造解析も行った。さらに、Ph-SMAPのRh錯体がケトンのヒドロシリル化や水素化の配位子として非常に優れていることを確認した。 シリカゲル表面上にシジ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。[Silica]-SMAPと[RhCl(C_2H_2)_2]_2から調製される表面固定化Rh錯体が嵩高いケトンのヒドロシリル化に非常に高い活性を示すことは、すでに明らかになっていたが、シリカ単体の構造を変えることにより、その活性を著しく向上させることに成功するとともに、嵩高いケトンの水素化にも成功した。さらに[Silica]-SMAP-Ir錯体による官能基化芳香族化合物のオルト位ボリル化反応も開発した。 2.かさ高いエンドキャップを持つトリエチニルホスフィンに関する研究 エンドキャップが異なる様々なトリエチニルホスフィンを合成し、その錯形成特性を検討した。その結果、かさ高いエンドキャップを持ち、半中空構造となった配位子が、様々な金属種に対して1:1錯体を形成することが確認できた。また、これらの半中空形配位子がRh触媒によるケトンのヒドロシリル化に対して優れた加速効果を示すことを明らかにした。 さらに、半中空形トリエチニルホスフィンを配位子とするカチオン性金(I)錯体のアルキン環化反応に対する触媒活性を検討し、ケトエステルの分子内付加反応(Conia-ene reaction)やエンイン環化異性か反応に対し、優れた触媒活性を示すことを明らかにした。すなわち、従来触媒では困難であった6-exo-digおよび7-exo-dig環化を可能にするとともに、立体障害のため進行しにくい内部アルキンの反応にも効果的であることを示した。
• 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

  研究期間 : 2006年 -2006年 

  代表者 : 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）

  研究期間 : 2002年 -2005年
• Atomic Level Organization of Transition Metal Complexes for Use in Organic Synthesis

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

  研究期間 : 2002年 -2005年
• 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

  研究期間 : 2001年 -2004年 

  代表者 : 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.
• メタロセン型修飾フラーレンの反応化学と材料科学

  日本学術振興会：科学研究費助成事業

  研究期間 : 2001年 -2002年 

  代表者 : 澤村 正也

   

  60個の炭素原子がサッカーボール状に結合した分子,[60]フラーレン(C60)は,1985年の発見当初より,特異な形状と巨大なπ電子共役系をもつことから,新しい機能性分子への応用が期待されてきた.本研究者は,有機金属化合物を用いたフラーレンの化学修飾の研究を進める中で,C_<60>に対する有機銅化合物の付加反応が,5重付加という極めて珍しい反応形式で定量的に進行し,シクロペンタジエン構造を持ったフラーレン誘導体C_<60>R_5Hを与えることを発見した.このシクロペンタジェン構造は脱プロトンにより6π電子系のシクロペンタジエニルアニオンへと変換できる.5炭素配位子であるシクロペンタジエニル(Cp)型配位子を含む金属錯体は有機金属化学において中心的な存在である.特にフェロセンに代表されるメタロセン型錯体は剛直な分子構造,化学的安定性,レドックス活性,および導電性などの特性を有することから,機能性材料としての応用を指向する研究が活発に行われている.本研究は,先に我々が開発した5炭素配位型フラーレン配位子FCpを利用して触媒や材料として有用な機能分子を合成することを目的として行ったものである. 具体的には,C60への有機基多重付加反応をより完成度の高い反応に磨き上げるとともに,これにより生成する分子を,フェロセンなどとのハイブリッド型有機金属分子や,有機フラーレン二分子膜ベシクルおよび極性カラム状液晶などの機能性分子集合体へと導いた.さらには,C60への有機銅5重付加反応を2度行うことにより,ダブルデッカー型ビスCpフラーレンを合成することに成功した.これは本研究を分子エレクトロニクス材料として期待される導電性ポリマーの開発へと導く重要な研究成果である.以下にこれらの成果を発表論文、総説および紹介記事等によって示す.
• 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

  研究期間 : 2001年 -2001年 

  代表者 : 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

  研究期間 : 2001年 -2001年 

  代表者 : 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

  研究期間 : 1997年 -1999年 

  代表者 : 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

  研究期間 : 1997年 -1999年 

  代表者 : 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

  研究期間 : 1998年 -1998年 

  代表者 : 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.
• 5炭素結合型フラーレン配位子を含む機能性有機金属錯体の合成

  日本学術振興会：科学研究費助成事業

  研究期間 : 1997年 -1998年 

  代表者 : 澤村 正也

   

  C_<60>に代表されるフラーレンはπ電子のネットワークが球面状に展開した特異な構造から多くの科学者の注目を集めている.本研究者は、その特異な電子構造、適度な大きさ、および三次元的な空間の広がりが、機能性有機金属錯体の基盤構造として適していると考え、新しいフラーレン配位子の開発を目指してフラーレンの化学修飾の研究に着手した.その結果,C_<60>と有機銅試薬(Ph_2Cu^-)の反応により,5つのPh基がC_<60>の1つの5員環の廻りを取り囲むように位置選択的に連続付加し,シクロペンタジエン構造を含むフラーレン誘導体C_<60>Ph_5Hが定量的な収率で得られることを見い出し,さらにこれを用いて幾つかの5炭素結合型フラーレン金属錯体を合成することにも成功した. 5炭素配位子であるシクロペンタジエニル(Cp)型配位子を含む金属錯体は有機金属化学において中心的な存在である.特にフェロセンに代表されるメタロセン型錯体は剛直な分子構造,化学的安定性,レドックス活性,および導電性などの特性を有することから,特に機能性材料としての応用を指向する研究が活発に行われている. 本研究によって,我々の合成した5炭素配位型フラーレン配位子を含む錯体が,光や電場などの外部刺激に対して応答性を示す可能性のある特異な電子構造を有していることが示された.C_<60>よりも高次のフラーレンであるC_<70>と有機銅試薬の反応によってインデニル骨格を有した3重付加体が得られることも明らかになった.またフラーレンの機能化の観点から,フラーレンの多重付加環化反応についても検討し,光学活性フラーレンの合成に成功するなどの成果を得ることもできた.
• 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

  研究期間 : 1996年 -1996年 

  代表者 : 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

  研究期間 : 1996年 -1996年 

  代表者 : 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

  研究期間 : 1996年 -1996年 

  代表者 : 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

  研究期間 : 1995年 -1995年 

  代表者 : 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

  研究期間 : 1991年 -1991年 

  代表者 : 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

  研究期間 : 1990年 -1990年 

  代表者 : 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

  研究期間 : 1988年 -1988年 

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

産業財産権

• 新規なトリアルキルホスフィン誘導体

  特開2004-262782