Researcher Database

Masaya Sawamura
Faculty of Science Chemistry Organic and Biological Chemistry
Professor

Researcher Profile and Settings

Affiliation

  • Faculty of Science Chemistry Organic and Biological Chemistry

Job Title

  • Professor

Degree

  • Kyoto University, Doctor of Engineering(Kyoto University)

J-Global ID

Research Interests

  • 有機金属化学   Organometallic Chemistry   

Research Areas

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

Academic & Professional Experience

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

Education

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

Association Memberships

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

Research Activities

Published Papers

  • Morisawa Takuto, Sawamura Masaya, Shimizu Yohei
    ORGANIC LETTERS 21 (18) 7466 - 7469 1523-7060 2019/09/20 [Refereed][Not invited]
  • Zhang Deliang, Iwai Tomohiro, Sawamura Masaya
    ORGANIC LETTERS 21 (15) 5867 - 5872 1523-7060 2019/08/02 [Refereed][Not invited]
  • Ueda Yusuke, Iwai Tomohiro, Sawamura Masaya
    CHEMISTRY-A EUROPEAN JOURNAL 25 (40) 9410 - 9414 0947-6539 2019/07/17 [Refereed][Not invited]
  • Yamazaki Yuki, Arima Nozomi, Iwai Tomohiro, Sawamura Masaya
    ADVANCED SYNTHESIS & CATALYSIS 361 (10) 2250 - 2254 1615-4150 2019/05/14 [Refereed][Not invited]
  • Reyes Ronald L, Iwai Tomohiro, Maeda Satoshi, Sawamura Masaya
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 141 (17) 6817 - 6821 0002-7863 2019/05/01 [Refereed][Not invited]
  • Akihiro Nishizawa, Tsuyoshi Takahira, Kosuke Yasui, Hayato Fujimoto, Tomohiro Iwai, Masaya Sawamura, Naoto Chatani, Mamoru Tobisu
    Journal of the American Chemical Society 141 (18) 7261 - 7265 0002-7863 2019/04 [Refereed][Not invited]
     
    © 2019 American Chemical Society. Herein, we describe a new catalytic approach to accessing aromatic amines from an abundant feedstock, namely phenols. The most reliable catalytic method for converting phenols to aromatic amines uses an activating group, such as a trifluoromethane sulfonyl group. However, this activating group is eliminated as a leaving group during the amination process, resulting in significant waste. Our nickel-catalyzed decarboxylation reaction of aryl carbamates forms aromatic amines with carbon dioxide as the only byproduct. As this amination proceeds in the absence of free amines, a range of functionalities, including a formyl group, are compatible. A bisphosphine ligand immobilized on a polystyrene support (PS-DPPBz) is key to the success of this reaction, generating a catalytic species that is significantly more active than simple nonsupported variants.
  • Imai Koji, Takayama Yurie, Murayama Hiroaki, Ohmiya Hirohisa, Shimizu Yohei, Sawamura Masaya
    ORGANIC LETTERS 21 (6) 1717 - 1721 1523-7060 2019/03/15 [Refereed][Not invited]
  • Arashima Junya, Iwai Tomohiro, Sawamura Masaya
    CHEMISTRY-AN ASIAN JOURNAL 14 (3) 411 - 415 1861-4728 2019/02/01 [Refereed][Not invited]
  • Iwai Tomohiro, Shibaike Kazutaka, Sawamura Masaya
    CHEMISTRY LETTERS 47 (9) 1162 - 1164 0366-7022 2018/09 [Refereed][Not invited]
  • Murakami Ryo, Sano Kentaro, Iwai Tomohiro, Taniguchi Tohru, Monde Kenji, Sawamura Masaya
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 57 (30) 9465 - 9469 1433-7851 2018/07/20 [Refereed][Not invited]
  • Konishi Shota, Iwai Tomohiro, Sawamura Masaya
    ORGANOMETALLICS 37 (12) 1876 - 1883 0276-7333 2018/06/25 [Refereed][Not invited]
  • Yuto Yasuda, Hirohisa Ohmiya, Masaya Sawamura
    Synthesis (Germany) 50 (11) 2235 - 2246 1437-210X 2018/06/01 [Refereed][Not invited]
     
    Details of the Cu-catalyzed enantioselective allyl-allyl coupling reaction between allylboronates and (Z)-allylic phosphates using a new chiral N -heterocyclic carbene (NHC) ligand containing a phenolic hydroxy group are presented. The copper catalysis delivers enantio-enriched chiral 1,5-dienes with a tertiary stereogenic center. Compatibility with various functional groups and the use of earth-abundant and relatively low-toxicity copper as a metal are attractive features of this protocol. The utility of the chiral phenol-NHC ligand for enantioselective copper catalysis with organoboron compounds is demonstrated and enantiodiscrimination models are discussed.
  • Tomohiro Iwai, Masahiro Ueno, Hiori Okochi, Masaya Sawamura
    Advanced Synthesis and Catalysis 360 (4) 670 - 675 1615-4169 2018/02/15 [Refereed][Not invited]
     
    Cationic gold(I) complexes with hollow-shaped triethynylphosphine ligands efficiently catalyzed intramolecular [2+2] cycloaddition of 1,9-enynes to afford cyclobutene-fused eight-membered carbocycles that were difficult to synthesize by other catalytic systems. Various 1,9-enynes with carbon linkers with or without a fused ring underwent efficient [2+2] cycloaddition with 5 mol% of the Au catalyst bearing the triarylmethyl-end-capped triethynylphosphine in CH2Cl2 at rt in the presence of MS 4A as an additive. More challenging 1,9-enyne substrates with fully saturated acyclic carbon linkers underwent eight-membered ring formation at 60 °C in ClCH2CH2Cl in the absence of MS 4A, forming monocyclic 1,3-dienes as major products. (Figure presented.).
  • Tomoya Harada, Yusuke Ueda, Tomohiro Iwai, Masaya Sawamura
    Chemical Communications 54 (14) 1718 - 1721 1364-548X 2018 [Refereed][Not invited]
     
    The Ni-catalyzed cross-coupling reaction between aryl fluorides and primary amines was enabled by the 1,2-bis(dicyclohexylphosphino)benzene (DCYPBz) or 1,2-bis(dicyclohexylphosphino)ethane (DCYPE) ligands. Both N-alkyl- and N-aryl-substituted primary amines participated in the selective reaction to form secondary amines. This protocol would potentially be useful for late-stage diversification of fluorinated compounds with complex structures for the synthesis of functionally interesting aniline derivatives.
  • Nagao, K., Yamazaki, A., Ohmiya, H., Sawamura, M.
    Organic Letters 20 (7) 1861 - 1865 1523-7060 2018 [Refereed][Not invited]
  • Martin C. Schwarzer, Akane Fujioka, Takaoki Ishii, Hirohisa Ohmiya, Seiji Mori, Masaya Sawamura
    Chemical Science 9 (14) 3484 - 3493 2041-6539 2018 [Refereed][Not invited]
     
    Copper-catalyzed asymmetric direct alkynylation of α-ketoesters with terminal alkynes with chiral prolinol-phosphine ligands, most preferably (αR,2S)-1-(2-dicyclohexylphosphinobenzyl)-α-neopentyl-2-pyrrolidinemethanol, afforded various enantioenriched chiral propargylic tertiary alcohols. Quantum-chemical calculations using the BP86 density functional including Grimme's empirical dispersion correction [DF-BP86-D3(BJ)-PCM(tBuOH)/TZVPP//DF-BP86-D3(BJ)/SVP] show the occurrence of OH⋯O/sp3-CH⋯O two-point hydrogen bonding between the chiral ligand and the carbonyl group of the ketoester in the stereo-determining transition states. Combined with the hydrogen-bonding interactions orienting the ketoester substrate, dispersive attractions between the chiral ligand (P-cyclohexyl groups) and the ketoester in the favored transition states, rather than steric repulsions in the disfavored transition state explain the enantioselectivity of the asymmetric copper catalysis.
  • Kentaro Hojoh, Yoshinori Shido, Hirohisa Ohmiya, Masaya Sawamura
    Chemistry Letters 47 (5) 632 - 635 1348-0715 2018 [Refereed][Not invited]
     
    A reductive CC-bond-forming cyclization of vinyl-terminated allyl chlorides via alkene hydroboration with 9-BBN-H followed by Cu-catalyzed asymmetric intramolecular allylic alkylation with a new chiral phosphoramidite ligand produced six-membered ring compounds with a tertiary or quaternary stereogenic center in the ring with high enantioselectivity.
  • Tomoya Harada, Yusuke Ueda, Tomohiro Iwai, Masaya Sawamura
    Chemical Communications 54 (14) 1718 - 1721 1364-548X 2018 [Refereed][Not invited]
     
    The Ni-catalyzed cross-coupling reaction between aryl fluorides and primary amines was enabled by the 1,2-bis(dicyclohexylphosphino)benzene (DCYPBz) or 1,2-bis(dicyclohexylphosphino)ethane (DCYPE) ligands. Both N-alkyl- and N-aryl-substituted primary amines participated in the selective reaction to form secondary amines. This protocol would potentially be useful for late-stage diversification of fluorinated compounds with complex structures for the synthesis of functionally interesting aniline derivatives.
  • Yamazaki, A., Nagao, K., Iwai, T., Ohmiya, H., Sawamura, M.
    Angewandte Chemie - International Edition Wiley-Blackwell 57 (12) 3196 - 3199 1433-7851 2018 [Refereed][Not invited]
  • Ronald L. Reyes, Tomoya Harada, Tohru Taniguchi, Kenji Monde, Tomohiro Iwai, Masaya Sawamura
    CHEMISTRY LETTERS 46 (12) 1747 - 1750 0366-7022 2017/12 [Refereed][Not invited]
     
    Enantioselective heteroatom-directed C(sp(3))-H borylation reactions of 2-aminopyridines and 2-alkylpyridines with Rh-and Ir catalytic systems using commercially available chiral monophosphine ligands, respectively, were developed. This methodology provides an innovative example of a homogeneous catalytic system for C(sp(3))-H borylation, and allows the direct synthesis of optically active alkylboronates with a moderate level of enantioselectivity.
  • Tomohiro Iwai, Kiichi Asano, Tomoya Harada, Masaya Sawamura
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 90 (8) 943 - 949 0009-2673 2017/08 [Refereed][Not invited]
     
    Polystyrene-cross-linking triphenylphosphines having methyl groups as ortho substituents were synthesized. Coordination of the polymer-bound tri(o-tolyl) phosphine-type ligand toward a Pd(II) complex was investigated by 31PCP/MASNMR spectroscopies. Effects of the ortho-methyl-substituent were evaluated in the Pd-catalyzed cross-coupling of aryl chlorides.
  • Takayoshi Yoshimura, Satoshi Maeda, Tetsuya Taketsugu, Masaya Sawamura, Keiji Morokuma, Seiji Mori
    CHEMICAL SCIENCE 8 (6) 4475 - 4488 2041-6520 2017/06 [Refereed][Not invited]
     
    We explored the reaction mechanism of the cationic rhodium(I)-BINAP complex catalysed isomerisation of allylic amines using the artificial force induced reaction method with the global reaction route mapping strategy, which enabled us to search for various reaction paths without assumption of transition states. The entire reaction network was reproduced in the form of a graph, and reasonable paths were selected from the complicated network using Prim's algorithm. As a result, a new dissociative reaction mechanism was proposed. Our comprehensive reaction path search provided rationales for the E/Z and S/R selectivities of the stereoselective reaction.
  • Takayoshi Yoshimura, Satoshi Maeda, Tetsuya Taketsugu, Masaya Sawamura, Keiji Morokuma, Seiji Mori
    CHEMICAL SCIENCE Royal Society of Chemistry ({RSC}) 8 (6) 4475 - 4488 2041-6520 2017/06 [Refereed][Not invited]
     
    We explored the reaction mechanism of the cationic rhodium(I)-BINAP complex catalysed isomerisation of allylic amines using the artificial force induced reaction method with the global reaction route mapping strategy, which enabled us to search for various reaction paths without assumption of transition states. The entire reaction network was reproduced in the form of a graph, and reasonable paths were selected from the complicated network using Prim's algorithm. As a result, a new dissociative reaction mechanism was proposed. Our comprehensive reaction path search provided rationales for the E/Z and S/R selectivities of the stereoselective reaction.
  • Yurie Takayama, Takaoki Ishii, Hirohisa Ohmiya, Tomohiro Iwai, Martin C. Schwarzer, Seiji Mori, Tohru Taniguchi, Kenji Monde, Masaya Sawamura
    CHEMISTRY-A EUROPEAN JOURNAL 23 (35) 8400 - 8404 0947-6539 2017/06 [Refereed][Not invited]
     
    Prolinol-phosphine chiral ligands enabled highly enantioselective copper-catalyzed intermolecular alkyne-nitrone coupling (Kinugasa reaction) to produce 1,3,4-trisubstituted chiral beta-lactams. A high level of enantiocontrol was achieved not only with aryl-or alkenylacetylenes but also with alkylacetylenes, which were important but unfavorable substrates in the previously reported protocols. Two-point hydrogen bonding between the chiral ligand and the nitrone oxyanion consisting of O-H center dot center dot center dot O and C(sp(3)) H center dot center dot center dot O hydrogen bonds is proposed.
  • Tomohiro Iwai, Tomoya Harada, Hajime Shimada, Kiichi Asano, Masaya Sawamura
    ACS CATALYSIS 7 (3) 1681 - 1692 2155-5435 2017/03 [Refereed][Not invited]
     
    A polystyrene-cross-linking bisphosphine PSDPPBz was synthesized through radical emulsion copolymer-ization between 4-t-butylstyrene as a monomer and tetraviny-lated 1,2-bis(diphenylphosphino)benzene (DPPBz) as a 4-fold cross-linker. The location of the DPPBz bisphosphine moiety at the branching points of the cross-linked network organic polymer allowed controlled bisphosphine monochelation to transition metals under conditions where homogeneous ligands may form bischelated single metal complexes or multinuclear complexes. PS-DPPBz showed high ligand performance in first-row transition metal catalysis, enabling challenging molecular Alkyl transformations that were not possible through the screening of existing homogeneous ligands. In the Ni-catalyzed amination of aryl chlorides with N-alkyl-substituted primary amines, the substrate scope has been expanded to include 2,6-disubstituted aryl chlorides and N-tertiary-alkyl-substituted primary amines. PS-DPPBz was effective for the Ni-catalyzed C-H/C-O coupling between 1,3-azoles and monocyclic aryl pivalates, which showed poor reactivity in the reported homogeneous catalytic system based on 1,2-bis(dicyclohexylphosphino)ethane (DCYPE). The usefulness of the polymer-cross-linking strategy was also demonstrated in alkene hydroboration reactions catalyzed by Cu or Co.
  • Kentaro Hojoh, Hirohisa Ohmiya, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY American Chemical Society ({ACS}) 139 (6) 2184 - 2187 0002-7863 2017/02 [Refereed][Not invited]
     
    A highly regio- and enantioselective copper catalyzed three-component coupling of isocyanides, hydrosilanes, and gamma,gamma-disubstituted allylic phosphates/chlorides to afford chiral alpha-quaternary formimides was enabled by the combined use of our original chiral naphthol-carbene ligand as a functional Cu-supporting ligand and LiOtBu as a stoichiometric Lewis base for Si. The formimides were readily converted to alpha-quaternary aldehydes.
  • Tomohiro Iwai, Ryotaro Tanaka, Masaya Sawamura
    ORGANOMETALLICS 35 (23) 3959 - 3969 0276-7333 2016/12 [Refereed][Not invited]
     
    A new class of triarylmethane-based phosphines (L1-L4) and their Pd(II) and Rh(I) complexes were synthesized and subsequently characterized by NMR spectroscopy and X-ray diffraction analysis. The reactions of these phosphines with [PdCl(pi-allyl)](2) gave the square-planar Pd(II) complexes [PdCl(pi-allyl)(L)] (L = L1-L4). The treatment of [PdCl(pi-allyl)(L3)] and [PdCl(pi-allyl)(L4)], which have CF3-substituted triarylmethane and 9-arylfluorene moieties, respectively, with LiOtBu afforded P,C(sp(3))-chelated palladacycle complexes. Reversibility between a C(sp(3))-M covalent bond and a C(sp(3))-H center dot center dot center dot M interaction was experimentally demonstrated using [RhCl(nbd)](2) as a Rh(I) source. The triarylmethane-monophosphines L1-L4 were applied to the Pd-catalyzed 1,4-addition of arylboronic acids to enones.
  • Yuto Yasuda, Hirohisa Ohmiya, Masaya Sawamura
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 55 (36) 10816 - 10820 1433-7851 2016/08 [Refereed][Not invited]
     
    Copper-catalyzed enantioselective allyl-allyl coupling between allylboronates and either Z-acyclic or cyclic allylic phosphates using a new chiral N-heterocyclic carbene ligand, bearing a phenolic hydroxy, is reported. This reaction occurs with exceptional S(N)2-type regioselectivities and high enantioselectivities to deliver chiral 1,5-diene derivatives with a tertiary stereogenic center at the allylic/homoallylic position.
  • Ryo Murakami, Tomohiro Iwai, Masaya Sawamura
    SYNLETT 27 (8) 1187 - 1192 0936-5214 2016/05 [Refereed][Not invited]
     
    Site-selective and stereoselective C(sp(3))-H borylation of alkyl side chains of 1,3-azoles with bis(pinacolato) diboron was effectively catalyzed by a silica-supported monophosphine-iridium catalyst. The borylation occurred under relatively mild conditions (2 mol% Ir, 5090 degrees C), affording the corresponding primary and secondary alkylboronates. This system was applicable to a variety of 1,3-(benzo) azoles such as thiazoles, oxazoles, and imidazoles.
  • Hirohisa Ohmiya, Heng Zhang, Saori Shibata, Ayumi Harada, Masaya Sawamura
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 55 (15) 4777 - 4780 1433-7851 2016/04 [Refereed][Not invited]
     
    Copper-catalyzed enantioselective allylic alkylation of azoles with ,-disubstituted primary allylic phosphates was achieved using a new chiral N-heterocyclic carbene ligand bearing a naphtholic hydroxy group. This reaction occurred with excellent branch regioselectivity and high enantioselectivity, thus forming a controlled all-carbon quaternary stereogenic center at the position to the heteroaromatic ring.
  • Murayama, H., Nagao, K., Ohmiya, H., Sawamura, M.
    Organic Letters 18 (7) 1706 - 1709 1523-7060 2016 [Refereed][Not invited]
  • Wakamatsu, T., Nagao, K., Ohmiya, H., Sawamura, M.
    Organometallics 35 (10) 1354 - 1357 0276-7333 2016 [Refereed][Not invited]
  • Tomohiro Iwai, Yuki Akiyama, Kiyoshi Tsunoda, Masaya Sawamura
    TETRAHEDRON-ASYMMETRY 26 (21-22) 1245 - 1250 0957-4166 2015/12 [Refereed][Not invited]
     
    The synthesis and characterization of a novel chiral phosphine phosphoric acid ligand, (R)-3-diphenylphosphino-1,1'-binaphthyl-2,2'-diyl hydrogenphosphate (2) and its rhodium(I) complexes are described. The single-crystal X-ray diffraction analysis of 2 showed the intermolecular hydrogen-bonding network of the phosphoric acid moiety. The reactions of 2 with [RhCl(cod)](2) in the presence of KOtBu or with [Rh(acac)(CO)(2)] (acac = acetylacetonate) gave P,O-chelating rhodium(I) complexes [Rh(2-H+)(cod)] 3 or [Rh(2-H+)(CO)](2) 4, respectively. Their molecular structures were determined by single-crystal X-ray diffraction. (C) 2015 Elsevier Ltd. All rights reserved.
  • Tomohiro Iwai, Shota Konishi, Tatsuya Miyazaki, Soichiro Kawamorita, Natsumi Yokokawa, Hirohisa Ohmiya, Masaya Sawamura
    ACS CATALYSIS 5 (12) 7254 - 7264 2155-5435 2015/12 [Refereed][Not invited]
     
    A silica-supported triptycene-type phosphine, Silica-TRIP, comprising a 9-phospha-10-silatriptycene (TRIP) and silica gel as a P-coordination center and a solid support, respectively, was synthesized and structurally characterized by nitrogen absorption measurements and solid-state CP/MAS NMR spectroscopy. Silica-TRIP exhibited a mono-P-ligating feature toward a Pd(II) complex, resulting in selective formation of a 1/1 Pd-P species even with an excess amount of the ligand. As a result, Silica-TRIP enabled Pd-catalyzed Suzuki-Miyaura cross-coupling reactions of chloroarenes under mild conditions, regardless of the moderate electrondonating nature of the triarylphosphine-based ligand.
  • Tomohiro Iwai, Masaya Sawamura
    ACS CATALYSIS 5 (9) 5031 - 5040 2155-5435 2015/09 [Refereed][Not invited]
     
    Quinoline is an important scaffold in many natural products, biologically active compounds, and functional materials. The C-H functionalization of quinoline scaffolds by transition metal catalysis provides an efficient method for rapidly obtaining substituted quinolines. This review summarizes recently reported transition-metal-catalyzed site-selective C-H functionalization of quinolines, excluding C2 selective reactions. A review of direct functionalization of quinoline N-oxides at the C8 position also is provided.
  • Nagao, K., Ohmiya, H., Sawamura, M.
    Organic Letters 17 (5) 1304 - 1307 1523-7060 2015 [Refereed][Not invited]
  • Murayama, H., Nagao, K., Ohmiya, H., Sawamura, M.
    Organic Letters 17 (9) 2039 - 2041 1523-7060 2015 [Refereed][Not invited]
  • Yasuda, Y., Nagao, K., Shido, Y., Mori, S., Ohmiya, H., Sawamura, M.
    Chemistry - A European Journal 21 (27) 9666 - 9670 0947-6539 2015 [Refereed][Not invited]
  • Hojoh, K., Shido, Y., Nagao, K., Mori, S., Ohmiya, H., Sawamura, M.
    Tetrahedron 71 (37) 6519 - 6533 0040-4020 2015 [Refereed][Not invited]
  • Morinaga, A., Nagao, K., Ohmiya, H., Sawamura, M.
    Angewandte Chemie - International Edition 54 (52) 15859 - 15862 1433-7851 2015 [Refereed][Not invited]
  • Wakamatsu, T., Nagao, K., Ohmiya, H., Sawamura, M.
    Beilstein Journal of Organic Chemistry 11 2444 - 2450 1860-5397 2015 [Refereed][Not invited]
  • Hirohisa Ohmiya, Masaya Sawamura
    JOURNAL OF SYNTHETIC ORGANIC CHEMISTRY JAPAN 72 (11) 1207 - 1217 0037-9980 2014/11 [Refereed][Not invited]
     
    This account describes our studies on the use of alkylboranes for copper-catalyzed allylic substitution and conjugate addition reactions. The wide availability of alkylboranes via the established alkene hydroboration reaction is an attractive feature of these transformations. Various functional groups are tolerated in the substrates. Catalytic mechanisms involving the formation of alkylcopper(I) species from alkylboranes through B/Cu transmetalation are proposed.
  • Tomohiro Iwai, Masaya Sawamura
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 87 (11) 1147 - 1160 0009-2673 2014/11 [Refereed][Not invited]
     
    Triethynylphosphines with bulky end caps such as triarylsilyl and triarylmethyl groups at allcyne termini have a novel molecular shape presenting a large, deep metal-binding cavity. The hollow-shaped triethynylphosphines functioned as effective ligands in the rhodium-catalyzed hydrosilylation of ketones with triorganosilanes due to the preferential formation of a mono-P-ligated rhodium species. Furthermore, the phosphines displayed remarkable rate enhancement in the gold(I)-catalyzed alkyne cyclization constructing six- to eight-membered ring compounds. It is proposed that the cavity in the ligand forces a nucleophilic center of the acetylenic compounds close to the gold-bound alkyne, making ring-closing anti attack feasible.
  • Ayumi Harada, Yusuke Makida, Tatsunori Sato, Hirohisa Ohmiya, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 136 (39) 13932 - 13939 0002-7863 2014/10 [Refereed][Not invited]
     
    The copper-catalyzed enantioselective allylic alkylation of terminal alkynes with primary allylic phosphates was developed by the use of a new chiral N-heterocyclic carbene ligand bearing a phenolic hydroxy group at the ortho position of one of the two N-aryl groups. This reaction occurred with excellent gamma-branch regioselectivity and high enantioselectivity, forming a controlled stereogenic center at the allylic/propargylic position. Various terminal alkynes, including silyl, aliphatic, and aromatic alkynes, could be used directly without premetalation of the C(sp)-H bond. On the basis of the results of experiments using an isomeric secondary allylic phosphate, which gave a branched product through a alpha-selective substitution reaction with retention of configuration, a reaction pathway involving 1,3-allylic migration of Cu in a ([sigma + pi]-allyl)copper(III) species is proposed.
  • Kenji Hara, Masaya Sawamura, Atsushi Fukuoka
    CHEMICAL RECORD 14 (5) 869 - 878 1527-8999 2014/10 [Refereed][Not invited]
     
    Catalysts are one of the key materials for realizing a sustainable society. However, we may encounter problematic cases where conventional catalyst systems cannot provide effective solutions. We thus believe that the establishment of novel methods of catalyst preparation is currently necessary. Utilization of high-density monolayers of molecular metal complexes is our strategy, and we expect that this methodology will enable facile and systematic screening of unique and efficient catalysts. This Personal Account describes our challenges to establish such an immature method in catalyst preparation as well as the related background and perspective. Preparation and catalysis by high-density monolayers of Rh complexes with N-heterocyclic carbene, structurally compact phosphine and diisocyanide ligands on gold surfaces are presented. The catalytic application of a high-density Pd-bisoxazoline complex prepared on a single-crystal silicon surface is also shown. Uniquely high catalyst turnover numbers and high chemoselectivities were observed with these catalyst systems.
  • Ryo Murakami, Kiyoshi Tsunoda, Tomohiro Iwai, Masaya Sawamura
    CHEMISTRY-A EUROPEAN JOURNAL 20 (41) 13127 - 13131 0947-6539 2014/10 [Refereed][Not invited]
     
    Heteroatom-directed C-H borylation of cyclopropanes and cyclobutanes was achieved with silica-supported monophosphane-Ir catalysts. Borylation occurred at the C-H bonds located gamma to the directing N or O atoms with exceptional cis stereoselectivity relative to the directing groups. This protocol was applied to the borylation of a tertiary C H bond of a ring-fused cyclopropane.
  • Kentaro Hojoh, Yoshinori Shido, Hirohisa Ohmiya, Masaya Sawamura
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 53 (19) 4954 - 4958 1433-7851 2014/05 [Refereed][Not invited]
     
    A combination of an in situ generated chiral Cu-I/DTBM-MeO-BIPHEP catalyst system and EtOK enabled the enantioselective S(N)2-type allylic cross-coupling between alkylborane reagents and ,-disubstituted primary allyl chlorides with enantiocontrol at a useful level. The reaction generates a stereogenic quaternary carbon center having three sp(3)-alkyl groups and a vinyl group. This protocol allowed the use of terminal alkenes as nucleophile precursors, thus representing a formal reductive allylic cross-coupling of terminal alkenes. A reaction pathway involving addition/elimination of a neutral alkylcopper(I) species with the allyl chloride substrate is proposed.
  • Tomohiro Iwai, Tomoya Harada, Ryotaro Tanaka, Masaya Sawamura
    CHEMISTRY LETTERS 43 (5) 584 - 586 0366-7022 2014/05 [Refereed][Not invited]
     
    Silica-supported tripod triarylphosphines that have a Ph3P-type core tripodally immobilized on a silica surface enabled the Pd-catalyzed borylation of chloroarenes with bis(pinacolato)di-boron under mild conditions. The immobilization in tripod was crucial for the excellent performance of the Ph3P-based ligands.
  • Tomohiro Iwai, Ryo Murakami, Tomoya Harada, Soichiro Kawamorita, Masaya Sawamura
    ADVANCED SYNTHESIS & CATALYSIS 356 (7) 1563 - 1570 1615-4150 2014/05 [Refereed][Not invited]
     
    A silica-supported tripod triarylphosphane (Silica-3p-TPP), containing a triphenylphosphane-type core tripodally immobilized on the silica surface, allows rhodium- and iridium-catalyzed C(sp(3))H borylations of amide, urea and alkylpyridine derivatives. The (PCP)-P-31/MAS NMR studies for the coordination behavior of the tripod phosphane towards a rhodium complex indicate efficient site isolation of the each phosphane center, allowing independent mono-P-coordination to the metal center.
  • Shota Konishi, Soichiro Kawamorita, Tomohiro Iwai, Patrick G. Steel, Todd B. Marder, Masaya Sawamura
    CHEMISTRY-AN ASIAN JOURNAL 9 (2) 434 - 438 1861-4728 2014/02 [Refereed][Not invited]
     
    Site-selective CH borylation of quinoline derivatives at the C8 position has been achieved by using a heterogeneous Ir catalyst system based on a silica-supported cage-type monophosphane ligand SMAP. The efficient synthesis of a corticotropin-releasing factor(1) (CRF1) receptor antagonist based on a late-stage CH borylation strategy demonstrates the utility of the C8 borylation reaction.
  • Tomohiro Iwai, Ryotaro Tanaka, Tomoya Harada, Masaya Sawamura
    CHEMISTRY-A EUROPEAN JOURNAL 20 (4) 1057 - 1065 0947-6539 2014/01 [Refereed][Not invited]
     
    A silica-supported triphenylphosphane (Silica-3p-TPP) with a Ph3P-type core, immobilized on a silica surface, was synthesized and characterized by nitrogen-absorption measurements and solid-state NMR spectroscopy. The tripodal immobilization constrains the mobility of the phosphane molecule and causes the lone pair on the phosphorus atom to face in the direction perpendicular to the support, resulting in the selective formation of a 1:1 metal-phosphane species that is free from unfavorable steric repulsions caused by the silica surface. Heterogeneous Pd catalysts created in this manner enabled room-temperature Suzuki-Miyaura cross-coupling reactions with unactivated chloroarenes, despite the moderate electronic and steric nature of the Ph3P-based ligands. These catalysts also showed potential in reactions with more challenging substrates under mild conditions. Tripodally immobilized and well-dispersed phosphanes on the silica surface were crucial for high catalytic activity.
  • Yutaka Matsuo, Yoichiro Kuninobu, Shingo Ito, Masaya Sawamura, Eiichi Nakamura
    DALTON TRANSACTIONS 43 (20) 7407 - 7412 1477-9226 2014 [Refereed][Not invited]
     
    Acylated buckyferrocene and ruthenocene, Fe(eta(5)-C60Me5)(eta(5)-C5H4COR)(R = Me, Ph, and CH=CHPh) and Ru(eta(5)-C60Me5)(eta(5)-C5H4COR) (R = Me and Ph), were obtained by Friedel- Crafts acylation of the parent buckymetallocenes with the corresponding acid chlorides and aluminum chloride in carbon disulfide at ambient temperature. The electron withdrawing and sterically hindered nature of the acyl groups were revealed by X-ray crystallography, infrared spectroscopy and electrochemical measurements. The possibility of further derivatizing the acylated products was illustrated by the conversion of the acetyl buckyruthenocene into the corresponding hydroxy and acetoxy compounds Ru(eta(5)-C60Me5)(eta(5)-C5H4CH-(OH)Me) and Ru(eta(5)-C60Me5)(eta(5)-C5H4CH(OAc)Me).
  • Nagao, K., Ohmiya, H., Sawamura, M.
    Journal of the American Chemical Society 136 (30) 10605 - 10608 0002-7863 2014 [Refereed][Not invited]
  • Tomohiro Iwai, Tomoya Harada, Kenji Hara, Masaya Sawamura
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 52 (47) 12322 - 12326 1433-7851 2013/11 [Refereed][Not invited]
  • Takamichi Wakamatsu, Kazunori Nagao, Hirohisa Ohmiya, Masaya Sawamura
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 52 (44) 11620 - 11623 1433-7851 2013/10 [Refereed][Not invited]
  • Takaoki Ishii, Ryo Watanabe, Toshimitsu Moriya, Hirohisa Ohmiya, Seiji Mori, Masaya Sawamura
    CHEMISTRY-A EUROPEAN JOURNAL 19 (40) 13547 - 13553 0947-6539 2013/09 [Refereed][Not invited]
     
    Catalyst-substrate hydrogen bonds in artificial catalysts usually occur in aprotic solvents, but not in protic solvents, in contrast to enzymatic catalysis. We report a case in which ligand-substrate hydrogen-bonding interactions cooperate with a transition-metal center in alcoholic solvents for enantioselective catalysis. Copper(I) complexes with prolinol-based hydroxy amino phosphane chiral ligands catalytically promoted the direct alkynylation of aldehydes with terminal alkynes in alcoholic solvents to afford nonracemic secondary propargylic alcohols with high enantioselectivities. Quantum-mechanical calculations of enantiodiscriminating transition states show the occurrence of a nonclassical sp(3)-CHO hydrogen bond as a secondary interaction between the ligand and substrate, which results in highly directional catalyst-substrate two-point hydrogen bonding.
  • Tomohiro Iwai, Yuki Akiyama, Masaya Sawamura
    TETRAHEDRON-ASYMMETRY 24 (12) 729 - 735 0957-4166 2013/06 [Refereed][Not invited]
     
    A chiral N-heterocyclic carbene (NHC) ligand 1a bearing a m-terphenyl-based phosphate moiety as an anionic N-substituent has been developed. A rhodium complex [Rh(1a)(cod)](2) was synthesized and its structure was characterized by NMR and ESI-MS spectroscopy. This ligand gave high enantioselectivities in copper-catalyzed enantioselective boron conjugate additions to an alpha,beta-unsaturated ester to give a chiral B-boryl ester. (C) 2013 Elsevier Ltd. All rights reserved.
  • Hideto Ito, Ayumi Harada, Hirohisa Ohmiya, Masaya Sawamura
    ADVANCED SYNTHESIS & CATALYSIS 355 (4) 647 - 652 1615-4150 2013/03 [Refereed][Not invited]
     
    The formation of six- and seven-membered ring ethers from hydroxy-tethered propargylic esters was efficiently catalyzed by a cationic gold(I) complex with a semihollow-shaped triethynylphosphane ligand. This gold catalysis showed a tolerance toward the reactions of primary, secondary, and tertiary alcohol substrates with various substitution patterns. A sterically congested 2,2,6,6-tetraalkyl-substituted tetrahydropyran derivative as well as 6,6- and 7,6-fused bicyclic diethers were obtained in useful yields. In addition, the gold catalysis was applicable to the reaction of a sulfonamide-tethered propargylic ester to give a piperidine derivative.
  • Soichiro Kawamorita, Ryo Murakami, Tomohiro Iwai, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 135 (8) 2947 - 2950 0002-7863 2013/02 [Refereed][Not invited]
     
    The site-selective activation and borylation of unactivated C(sp(3))-H bonds in 2-alkylpyridines to form primary and secondary alkylboronates was achieved using silica-supported monophosphine-Ir catalysts. This borylation occurs selectively at C-H bonds located gamma to the pyridine nitrogen atom. The site-selectivity of this reaction suggests that the C-H bond cleavage occurs with the assistance of a proximity effect due to N-to-Ir coordination.
  • Tomohiro Iwai, Hiori Okochi, Hideto Ito, Masaya Sawamura
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 52 (15) 4239 - 4242 1433-7851 2013 [Refereed][Not invited]
  • Yusuke Makida, Yurie Takayama, Hirohisa Ohmiya, Masaya Sawamura
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 52 (20) 5350 - 5354 1433-7851 2013 [Refereed][Not invited]
  • Soichiro Kawamorita, Kenji Yamazaki, Hirohisa Ohmiya, Tomohiro Iwai, Masaya Sawamura
    ADVANCED SYNTHESIS & CATALYSIS 354 (18) 3440 - 3444 1615-4150 2012/12 [Refereed][Not invited]
     
    A silica-supported, cage-type, compact phosphane (Silica-SMAP) was used for the copper-catalyzed conjugate reduction of a,beta-unsaturated carbonyl and carboxyl compounds with poly(methylhydrosiloxane) (PMHS). The heterogeneous catalyst system showed high activity and chemoselectivity, and was easily separable from the reaction mixture after the reaction. Furthermore, the catalyst was reusable without loss of its high catalytic activity or selectivity.
  • Yoshinori Shido, Mika Yoshida, Masahito Tanabe, Hirohisa Ohmiya, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 134 (45) 18573 - 18576 0002-7863 2012/11 [Refereed][Not invited]
     
    The first catalytic enantioselective allylic substitution reaction with alkylboron compounds has been achieved. The reaction between alkyl-9-BBN reagents and primary allylic Chlorides proceeded With excellent gamma-selectivities and high enantioselectivities under catalysis. of a Cu(I)-DTBM-SEGPHOS system. The protocol produces terminal alkenes with an allylic stereogenic center branched With functionalized sp(3)-alkyl groups. The reaction with a gamma-silicon-substituted allyl chloride affords an efficient strategy for the enantioselective synthesis of functionalized alpha-stereogenic chiral allylsilanes.
  • Enantioselective Conjugate Addition of Alkylboranes Catalyzed by a Copper-N-Heterocyclic Carbene Complex
    Masaya Sawamura, Hirohisa Ohmiya, Mika Yoshida
    SYNTHESIS-STUTTGART 44 (21) A115 - A117 0039-7881 2012/11 [Refereed][Not invited]
  • Umi Yokobori, Hirohisa Ohmiya, Masaya Sawamura
    ORGANOMETALLICS 31 (22) 7909 - 7913 0276-7333 2012/11 [Refereed][Not invited]
     
    Copper-catalyzed gamma-selective coupling between gamma-silylated propargylic phosphates and alkylboron compounds (alkly-9-BBN, prepared by hydroboration of alkenes with 9-BBN-H) Produced allenylsilanes with exceptional selectivity. The reaction tolerated various functional groups in both the alkylboranes and the propargylic Phosphates to afford functionalized allenylsilanes. The reaction of enantioenriched gamma-silylated propargylic: phosphates proceeded with excellent: 1,3-anti stereoselectivity to give axially. chiral allenylsilanes.
  • Soichiro Kawamorita, Tatsuya Miyazaki, Tomohiro Iwai, Hirohisa Ohmiya, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 134 (31) 12924 - 12927 0002-7863 2012/08 [Refereed][Not invited]
     
    Direct C(sp(3))-H borylation of amides, ureas, and 2-aminopyridine derivatives at the position alpha to the N atom, which gives the corresponding alpha-aminoalkylboronates, has been achieved with a heterogeneous catalyst system consisting of [Rh(OMe)(cod)](2) and a silica-supported triarylphosphine ligand (Silica-TRIP) that features an immobilized triptycene-type cage structure with a bridgehead P atom. The reaction occurs not only at terminal C-H bonds but also at internal secondary C-H bonds under mild reaction conditions (25-100 degrees C, 0.1-0.5 mol % Rh).
  • Mika Yoshida, Hirohisa Ohmiya, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 134 (29) 11896 - 11899 0002-7863 2012/07 [Refereed][Not invited]
     
    The first catalytic enantioselective conjugate addition of alkylboron compounds has been achieved. Reactions between alkylboranes and imidazol-2-yl alpha,beta-unsaturated ketones proceeded with high enantioselectivity under the influence of a Cu(I) catalyst system, prepared in situ from CuCl, a new chiral imidazolium salt as a precursor for the N-heterocyclic carbene ligand, and PhOK. Alkylboranes are widely obtained via alkene hydroboration. A variety of functional groups are tolerated in alkylboranes and alpha,beta-unsaturated ketones.
  • Dong Li, Hirohisa Ohmiya, Masaya Sawamura
    SYNTHESIS-STUTTGART 44 (9) 1304 - 1307 0039-7881 2012/05 [Refereed][Not invited]
     
    Copper-catalyzed allylic alkylation of ketene silyl acetals proceeded with excellent gamma-E-selectivity. Efficient alpha-to-gamma chirality transfer with anti-selectivity occurred in the reaction of enantioenriched secondary allylic phosphates, affording enantioenriched beta-branched gamma,delta-unsaturated esters. The reaction was readily scalable and highly reliable in terms of product yield and stereoselectivities.
  • Kazunori Nagao, Hirohisa Ohmiya, Masaya Sawamura
    SYNTHESIS-STUTTGART 44 (10) 1535 - 1541 0039-7881 2012/05 [Refereed][Not invited]
     
    A copper-catalyzed gamma-selective allyl-alkyl coupling between gamma-silylated allylic phosphates and alkylboron compounds (alkyl-9-BBN, prepared by hydroboration of alkenes with 9-BBN-H) produced allylsilanes. The reaction tolerated various functional groups in both the alkylboranes and the allylic phosphates, and afforded functionalized allylsilanes.
  • Kazunori Nagao, Umi Yokobori, Yusuke Makida, Hirohisa Ohmiya, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 134 (21) 8982 - 8987 0002-7863 2012/05 [Refereed][Not invited]
     
    The stereochemical courses of the copper-catalyzed allyl-alkyl coupling between enantioenriched chiral allylic phosphates and alkylboranes were switchable between 1,3-anti and 1,3-syn selectivities by the choice of solvents and achiral alkoxide bases with different steric demands. The reactions with gamma-silylated allylic phosphates allow efficient synthesis of enantioenriched chiral allylsilanes with tertiary or quaternary carbon stereogenic centers. Cyclic and acyclic bimodal participation of alkoxyborane species in an organocopper addition-elimination sequence is proposed to account for the phenomenon of the anti/syn-stereochemical reversal.
  • Hajime Ito, Takanori Miya, Masaya Sawamura
    TETRAHEDRON 68 (17) 3423 - 3427 0040-4020 2012/04 [Refereed][Not invited]
     
    We have developed a useful procedure for borylation using catalytic CuCl/Xantphos and stoichiometric K(O-t-Bu): the highly versatile method is suitable for the synthesis of allylboronates including those with terminal and internal allylic systems, cyclic structures, and functional groups. Optically active allylboronates were synthesized from prochiral substrates with a chiral diphosphine ligand using this procedure. The reaction rate is generally higher than the original Cu(O-t-Bu)/ligand catalyst system, which we previously reported. (C) 2011 Elsevier Ltd. All rights reserved.
  • Hajime Ito, Yuko Horita, Masaya Sawamura
    ADVANCED SYNTHESIS & CATALYSIS 354 (5) 813 - 817 1615-4150 2012/03 [Refereed][Not invited]
     
    We report the first copper(I)-catalyzed reaction between a disilane and allylic carbonates to produce allylsilanes. The silyl nucleophilic substitution proceeded primarily in a SN2 fashion whereas SN2' products were also obtained through s-p-s isomerization of the copper(III) intermediate depending on the substrates steric bulk.
  • Mingyu Yang, Natsumi Yokokawa, Hirohisa Ohmiya, Masaya Sawamura
    ORGANIC LETTERS 14 (3) 816 - 819 1523-7060 2012/02 [Refereed][Not invited]
     
    A Cu-catalyzed gamma-selective coupling reaction between propargylic phosphates and aryl- or alkenylboronates afforded aryl- or alkenyl-conjugated allenes. The reaction showed excellent functional group compatibility in both the propargylic substrates and the boronates. The reaction of an enantioenriched propargylic phosphate proceeded with excellent chirality transfer with 1,3-anti stereochemistry to give axially chiral aryl- and alkenylallenes.
  • Yusuke Makida, Hirohisa Ohmiya, Masaya Sawamura
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 51 (17) 4122 - 4127 1433-7851 2012 [Refereed][Not invited]
  • Soichiro Kawamorita, Tatsuya Miyazaki, Hirohisa Ohmiya, Tomohiro Iwai, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 133 (48) 19310 - 19313 0002-7863 2011/12 [Refereed][Not invited]
     
    Supported phosphine-Rh systems, prepared in situ from silica-supported bridgehead monophosphines and [Rh(OH)(cod)]2, have enabled ortho-selective C-H borylation for a range of arenes containing nitrogen-based directing groups. The regioselectivity was excellent with various N-directing groups, including saturated and unsaturated N-heterocycles, tert-aminoalkyl groups, and iminetype C-N double bonds. The reaction showed significant tolerance toward steric repulsion around the reacting C-H bond. This Rh catalysis complements the Jr-catalyzed orthoborylation, which is effective for arenes with oxygen-based directing groups.
  • Hirohisa Ohmiya, Umi Yokobori, Yusuke Makida, Masaya Sawamura
    ORGANIC LETTERS 13 (23) 6312 - 6315 1523-7060 2011/12 [Refereed][Not invited]
     
    Copper-catalyzed gamma-selective coupling between propargylic phosphates and alkylboron compounds (alkyl-9-BBN, prepared by hydroboration of alkenes with 9-BBN-H) affords multisubstituted allenes with various functional groups. The reaction of enantioenriched propargylic phosphates to give axially chiral allenes proceeds with excellent point-to-axial chirality transfer with 1,3-anti stereochemistry.
  • Hirohisa Ohmiya, Yoshinori Shido, Mika Yoshida, Masaya Sawamura
    CHEMISTRY LETTERS 40 (9) 928 - 930 0366-7022 2011/09 [Refereed][Not invited]
     
    Conjugate addition of alkylboron compounds (alkyl-9-BBN) to aryl alpha,beta-unsaturated ketones proceeded in the presence of a catalytic amount (10 mol %) of [(IPr)CuCl] and t-BuOK. The alkylboranes are available through alkene hydroboration, and thus the overall process represents a reductive conjugate addition of alkenes to enone derivatives. A variety of functional groups are tolerated in both the alkenes and the alpha,beta-unsaturated ketones.
  • Yusuke Sasaki, Masaya Sawamura, Hajime Ito
    CHEMISTRY LETTERS 40 (9) 1044 - 1046 0366-7022 2011/09 [Refereed][Not invited]
     
    The reaction of enantioenriched allenylboronate 3a (98% ee) with benzaldehyde gave homopropargylic alcohol syn- and anti-4b with anomalous syn addition selectivity (anti:syn = 29:71) and high cc (98% and 97%, respectively). The stereochemical outcome in terms of the absolute configuration shows that this reaction proceeds through a cyclic transition state. Density functional theoretical (DFT) calculations were carried out to elucidate the mechanism of this anomalous syn-selectivity.
  • Hideto Ito, Tomoya Harada, Hirohisa Ohmiya, Masaya Sawamura
    BEILSTEIN JOURNAL OF ORGANIC CHEMISTRY 7 951 - 959 1860-5397 2011/07 [Refereed][Not invited]
     
    The gold-catalyzed, seven-membered ring forming, intramolecular hydroamination of alkynic sulfonamides has been investigated. The protocol, with a semihollow-shaped triethynylphosphine as a ligand for gold, allowed the synthesis of a variety of azepine derivatives, which are difficult to access by other methods. Both alkynic sulfoamides with a flexible linear chain and the benzene-fused substrates underwent 7-exo-dig cyclization to afford the nitrogen-containing heterocyclic seven-membered rings, such as tetrahydroazepine and dihydrobenzazepine, in good yields.
  • Dong Li, Hirohisa Ohmiya, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 133 (15) 5672 - 5675 0002-7863 2011/04 [Refereed][Not invited]
     
    Copper-catalyzed allylic alkylation of ketene silyl acetals proceeded with excellent gamma-E-selectivity. Efficient alpha-to-gamma chirality transfer with anti-selectivity occurred in the reaction of enantioenriched secondary allylic phosphates, affording enantioenriched beta-branched gamma,delta-unsaturated esters. Excellent functional group compatibility was observed.
  • Hirohisa Ohmiya, Masahito Tanabe, Masaya Sawamura
    ORGANIC LETTERS 13 (5) 1086 - 1088 1523-7060 2011/03 [Refereed][Not invited]
     
    Carboxylation of alkylboron compounds (alkyl-9-BBN) with CO2 proceeded in the presence of catalytic amounts of CuOAc/1,10-phenanthroline and a stoichiometric amount of (KOBu)-Bu-t. The alkylboranes are easily and widely available through the alkene hydroboration, and thus the overall process represents a reductive carboxylation of alkenes with CO2. The broad functional group compatibility and the inexpensiveness of the Cu/1,10-phenathoroline catalyst system are attractive features of this protocol.
  • Hirohisa Ohmiya, Mika Yoshida, Masaya Sawamura
    ORGANIC LETTERS 13 (3) 482 - 485 1523-7060 2011/02 [Refereed][Not invited]
     
    Conjugate addition of alkylboron compounds (allryl-9-BBN) to imidazol-2-yl alpha,beta-unsaturated ketones proceeded in the presence of a catalytic amount (10 mol %) of CuCl, 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes), and t-BuOK. The alkylboranes are available through alkene hydroboration, and thus the overall process represents a reductive conjugate addition of alkenes to enone derivatives. A variety of functional groups are tolerated in both the alkenes and the alpha,beta-unsaturated ketones. The 2-acylimidazole moiety can easily be converted into the corresponding carboxylic acid, ester, and amide derivatives.
  • Soichiro Kawamorita, Hirohisa Ohmiya, Tomohiro Iwai, Masaya Sawamura
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 50 (36) 8363 - 8366 1433-7851 2011 [Refereed][Not invited]
  • Hajime Ito, Shun Kunii, Masaya Sawamura
    NATURE CHEMISTRY 2 (11) 972 - 976 1755-4330 2010/11 [Refereed][Not invited]
     
    Asymmetric reactions that transform racemic mixtures into enantio-enriched products are in high demand, but classical kinetic resolution produces enantiopure compounds in <50% yield even in an ideal case. Many deracemization processes have thus been developed including dynamic kinetic resolution and dynamic kinetic asymmetric transformation, which can provide enantio-enriched products even after complete conversion of the racemic starting materials. However, these dynamic processes require racemization or symmetrization of the substrates or intermediates. We demonstrate a direct chemical enantio-convergent transformation without a racemization or symmetrization process. Copper(I)-catalysed asymmetric allylic substitution of a racemic allylic ether afforded a single enantiomer of an a-chiral allylboronate with complete conversion and high enantioselectivity (up to 98% enantiomeric excess). One enantiomer of the substrate undergoes an anti-S(N)2'-type reaction whereas the other enantiomer reacts via a syn-S(N)2' pathway. The products, which cannot be prepared by dynamic procedures, have been used to construct all-carbon quaternary stereocentres.
  • Hideto Ito, Hirohisa Ohmiya, Masaya Sawamura
    ORGANIC LETTERS 12 (19) 4380 - 4383 1523-7060 2010/10 [Refereed][Not invited]
     
    A cationic gold(I) complex bearing a semihollow-shaped triethynylphosphine ligand efficiently catalyzed the 7-exo-dig cyclization of silyl enol ethers with an omega-alkynic substituent. The reaction gave various methylenecycloheptane derivatives with an exo- or endocyclic carbonyl group. The protocol was applicable not only to cyclic substrates that form bicyclic frameworks but also to acyclic ones with or without substituents in a carbon chain tether.
  • Hirohisa Ohmiya, Mika Yoshida, Masaya Sawamura
    SYNLETT (14) 2136 - 2140 0936-5214 2010/09 [Refereed][Not invited]
     
    An efficient approach to hydroxylated pyrrolidine and piperidine derivatives through the intramolecular hydroamination catalyzed by a Cu(I)-Xantphos system is described. The transformation allows for the short synthesis of N-alkylated aza-sugars without a protection-deprotection event of the hydroxy groups.
  • Kenji Yamazaki, Soichiro Kawamorita, Hirohisa Ohmiya, Masaya Sawamura
    ORGANIC LETTERS 12 (18) 3978 - 3981 1523-7060 2010/09 [Refereed][Not invited]
     
    The directed ortho borylation of phenol derivatives protected with an N,N-diethylcarbamoyl group was efficiently catalyzed by an immobilized monophosphine-Ir system, which was prepared in situ from [Ir(OMe)(cod)](2) and a silica-supported, compact phosphine. The utility of the carbamoyloxy group as a leaving group for metal-catalyzed cross-coupling reactions was demonstrated by its utilization in the synthesis of a terphenyl derivative.
  • Chongmin Zhong, Shun Kunii, Yuki Kosaka, Masaya Sawamura, Hajime Ito
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 132 (33) 11440 - 11442 0002-7863 2010/08 [Refereed][Not invited]
     
    A new asymmetric route for the synthesis of trans-2-aryl- and -heteroaryl-substituted cyclopropylboronates has been developed. (Z)-3-arylallylic phosphates were converted to the optically active products with high yield and diastereo- and enantioselectivity through a copper(I)-catalyzed reaction with a diboron derivative. Under mild reaction conditions, the reaction affords the arylcyclopropane products with a functional group and a heteroaromatic group in a highly enantioselective manner. When (E)-allylic phosphates were used as substrates, a ligand-controlled product switch between the trans and cis configurations was observed.
  • Dong Li, Tatsunori Tanaka, Hirohisa Ohmiya, Masaya Sawamura
    ORGANIC LETTERS 12 (15) 3344 - 3347 1523-7060 2010/08 [Refereed][Not invited]
     
    A palladium-catalyzed gamma-selective allyl -aryl coupling between gamma-silylated allylic esters and arylboronic acids produced alpha-arylated allylsilanes with E-alkene geometry. The reaction tolerated various functional groups In both the arylboronic acids and the allylic esters and afforded functionalized allylsilanes. The reaction of optically active allylic esters took place with excellent alpha-to-gamma chirality transfer with syn stereochemistry to give chiral allylsilanes.
  • Soichiro Kawamorita, Hirohisa Ohmiya, Masaya Sawamura
    JOURNAL OF ORGANIC CHEMISTRY 75 (11) 3855 - 3858 0022-3263 2010/06 [Refereed][Not invited]
     
    The ester-directed regioselective borylation of arenes catalyzed by a silica-supported monophosphine-Ir complex displayed a significantly broad substrate scope toward heteroaromatic compounds, including thiophene. pyrrole, furan, benzothiophene, benzofuran, indole, and carbazole derivatives. The regioselectivity is complementary to the selectivities observed in the heteroarene C-H borylation with the dtbpy-Ir catalyst system.
  • Hajime Ito, Takashi Toyoda, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 132 (17) 5990 - + 0002-7863 2010/05 [Refereed][Not invited]
     
    A copper(I)-catalyzed stereospecific reaction for the preparation of cis- and trans-1-silyl-2-borylcyclobutanes as well as 1-phenyl-2-borylcyclobutanes is reported. (Z)- and (E)-Homoallylic methanesulfonates were converted to the corresponding trans- and cis-cyclobutane derivatives, respectively, in the presence of a CuCl/dppp catalyst, bis(pinacolato)diboron, and K(O-t-Bu)/THF. Stereospecific derivatizations of the cis- and trans-borylcyclobutanes were carried out to demonstrate the utility of the borylcyclobutanes.
  • Hirohisa Ohmiya, Natsumi Yokokawa, Masaya Sawamura
    ORGANIC LETTERS 12 (10) 2438 - 2440 1523-7060 2010/05 [Refereed][Not invited]
     
    A Cu-catalyzed allyl-aryl coupling reaction between (2)-acyclic or cyclic allylic phosphates and arylboronates proceeds with excellent gamma-E-selectivity and 1,3-anti chirality transfer, which gives the corresponding coupling products with benzylic and allylic stereogenic centers. The wide availability and easy-to-handle nature of arylboronates, the inexpensiveness of the Cu catalyst system, and the high regio- and stereoselectivities are attractive features of this protocol.
  • Hirohisa Ohmiya, Mingyu Yang, Yoshihiro Yamauchi, Yuhki Ohtsuka, Masaya Sawamura
    ORGANIC LETTERS 12 (8) 1796 - 1799 1523-7060 2010/04 [Refereed][Not invited]
     
    Ligand-controlled regioselective palladium-catalyzed decarboxylative hydrogenolysis of propargylic formates is described. A wide range of allenes and alkynes were obtained by using either 1,2-diphenylphosphinoethane (DPPE) or 1,6-bisdiphenylphosphinohexane (DPPH) as a catalyst ligand.
  • Hirohisa Ohmiya, Umi Yokobori, Yusuke Makida, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 132 (9) 2895 - + 0002-7863 2010/03 [Refereed][Not invited]
     
    Copper-catalyzed allyl-alkyl coupling between allylic phosphates and alkylboranes, prepared by hydroboration of alkenes with 9-BBN-H, takes place with complete gamma- and E-selectivities and with preferential 1,3-anti stereochemistry. The reaction tolerates various functional groups in both the allylic phosphate and alkylborane. Catalytic mechanisms involving transmetalation between a trialkyl(alkoxo)borate and a copper(I) complex to form an alkylcopper(I) species are proposed.
  • Catalysis with densely packed monolayer of metal-phosphine complex on gold surface
    Kenji Hara, Ryuto Akiyama, Kohei Uosaki, Atsushi Fukuoka, Masaya Sawamura
    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 239 0065-7727 2010/03 [Refereed][Not invited]
  • Yusuke Sasaki, Chongmin Zhong, Masaya Sawamura, Hajime Ito
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 132 (4) 1226 - + 0002-7863 2010/02 [Refereed][Not invited]
     
    Copper(I)-catalyzed asymmetric monoborylation of 1,3-dienes has been developed. We describe the production of either optically active homoallyl- or allylboronates with high regio- and enantioselectivity (88-97% ee) through monoborylation of 1,3-dienes. The reaction with 1,3-cyclohexadiene derivatives afforded the corresponding enantioenriched homoallyboronates. By simply changing the reaction conditions, a drastic change of product preference between homoallyl- and allylboronates was found in the reaction of 1,3-cyclopentadiene and 1,3-cycloheptadiene.
  • Hirohisa Ohmiya, Yusuke Makida, Dong Li, Masahito Tanabe, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 132 (2) 879 - 889 0002-7863 2010/01 [Refereed][Not invited]
     
    Reactions between acyclic (E)-allylic acetates and arylboronic acids in the presence of a palladium catalyst prepared from Pd(OAc)(2), phenanthroline (or bipyridine), and AgSbF(6) (1:1.2:1) proceeded with excellent gamma-selectivity to afford allyl-aryl coupling products with E-configuration. The reactions of a-chiral allylic acetates took place with excellent alpha-to-gamma chirality transfer with syn stereochemistry to give allylated arenes with a stereogenic center at the benzylic position. The reaction tolerated a broad range of functional groups in both the allylic acetates and the arylboronic acids. Furthermore, gamma-arylation of cinnamyl alcohol derivatives afforded gem-diarylalkane derivatives containing an unconjugated alkenic substituent. The synthetic utility of this method was demonstrated by its utilization in an efficient synthesis of (+)-sertraline, an antidepressant agent. The observed gamma-regioselectivity and E-1,3-syn stereochemistry were rationalized based on a Pd(II) mechanism involving transmetalation between a cationic mono(acyloxo)palladium(II) complex and arylboronic acid, and directed carbopalladation followed by syn-beta-acyloxy elimination. The results of stoichionnetric reactions of palladium complexes related to possible intermediates were fully consistent with the proposed mechanism.
  • Hajime Ito, Takuma Okura, Kou Matsuura, Masaya Sawamura
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 49 (3) 560 - 563 1433-7851 2010 [Refereed][Not invited]
  • Hirohisa Ohmiya, Hideto Ito, Masaya Sawamura
    ORGANIC LETTERS 11 (24) 5618 - 5620 1523-7060 2009/12 [Refereed][Not invited]
     
    The Rh-catalyzed coupling reaction between propargylic carbonates and a silylboronate afforded allenylsilanes with different substitution patterns in high yields. The reaction tolerates a variety of functional groups in propargylic carbonates. The reaction of an optically active propargylic carbonate proceeded with excellent chirality transfer with 1,3-anti stereochemistry to give an axially chiral allenylsilane.
  • Hajime Ito, Tomohisa Saito, Takahiro Miyahara, Chongmin Zhong, Masaya Sawamura
    ORGANOMETALLICS 28 (16) 4829 - 4840 0276-7333 2009/08 [Refereed][Not invited]
     
    Gold hydride is a rare transition-metal species. Despite the fact that gold hydrides may be key intermediates in several gold-catalyzed reactions, their chemical properties are not well understood. We report the synthesis, characterization, and catalytic properties of gold(I) hydride species that play an important role in a gold(I)-catalyzed dehydrogenative alcohol silylation. Tricoordinated complexes AuCl(xantphos) (1a) and AuCl(xy-xantphos) (1b) were prepared and characterized by (1)H and (31)P{(1)H} NMR measurements and X-ray crystallography. Gold(I) hydride species 6b generated from the reaction between 1b and PhMe(2)SiH (4b) in CDCl(3) was characterized by (1)H and (31)P NMR measurements and ESI-MS spectrometry. NMR and kinetic studies reveald that the reaction mechanism involves the gold(I) hydride species as a key intermediate. The high catalytic activities of 1a and 1b in dehydrogenative alcohol silylation are explained by the stability of the tricoordinated chelating structure and the activation of the Au-Cl bond induced by the stereoelectronic effect of the coordinating phosphorus atoms. This study reports the first example of a gold(I) hydride complex that exhibits catalytic activity.
  • Hirohisa Ohmiya, Toshimitsu Moriya, Masaya Sawamura
    ORGANIC LETTERS 11 (10) 2145 - 2147 1523-7060 2009/05 [Refereed][Not invited]
     
    The Cu-Xantphos system [Cu(O-t-Bu)-Xantphos, 10-15 mol %] catalyzes the intramolecular hydroamination of unactivated terminal alkenes bearing an unprotected aminoalkyl substituent in alcoholic solvents, giving pyrrolidine and piperidine derivatives in excellent yields. This system is applicable to both primary and secondary amines and tolerates a variety of functional groups.
  • Soichiro Kawamorita, Hirohisa Ohmiya, Kenji Hara, Atsushi Fukuoka, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 131 (14) 5058 - + 0002-7863 2009/04 [Refereed][Not invited]
     
    An immobilized monophosphine-Ir system, which was prepared in situ from [Ir(OMe)(cod)](2) and a silica-supported, compact phosphine, showed high activities and selectivities for the borylation of aromatic C-H bonds with bis(pinacolato)diboron. This system was effective not only for the borylation of benzene but also for the ortho borylation of arenes with directing groups, such as ester, amide, sulfonate, acetal, alkoxymethyl, and chloro groups, under mild reaction conditions.
  • Chongmin Zhong, Yusuke Sasaki, Hajime Ito, Masaya Sawamura
    CHEMICAL COMMUNICATIONS (39) 5850 - 5852 1359-7345 2009 [Refereed][Not invited]
     
    Cu(I)-catalyzed anti-S(N)2'-type reduction of internal propargylic carbonates with hydrosilanes affords various di- and trisubstituted allenes with high regioselectivities; the reactions are compatible with functional groups and work efficiently for the synthesis of optically-active allenes.
  • Go Hamasaka, Soichiro Kawamorita, Atsuko Ochida, Ryuto Akiyama, Kenji Hara, Atsushi Fukuoka, Kiyotaka Asakura, Wang Jae Chun, Hirohisa Ohmiya, Masaya Sawamura
    ORGANOMETALLICS 27 (24) 6495 - 6506 0276-7333 2008/12 [Refereed][Not invited]
     
    Solid-supported phosphine ligands silica-SMAPs {[silica gel 60N]-SMAP (1a) or [CARiACT Q-10]-SMAP (1b)}, which are composed of a caged, compact trialkylphosphine (SMAP) as a ligand and silica gel (silica get 60N or CARiACT Q-10) as a support,'were synthesized through surface functionalization. The supported phosphines (1a,b) were structurally characterized by solid-state (13)C, (29)Si, and (31)P cross-polarization/magic angle spinning (CP/MAS) NMR spectroscopies and N(2) adsorption measurements. Complexation of 1a,b with [RhCl(cod)](2) afforded a mono(phosphine)-rhodium complex Silica-SMAP-RhCl(cod) exclusively, even in the presence of excess ligands, as proved by solid-state (13)C and (31)P CP/MAS NMR spectroscopies and Rh K-edged X-ray'absorption fine structure (XAFS) measurements. Heterogeneous catalysts that were prepared from [RhCl(C(2)H(4))(2)](2) and 1a,b showed exceptionally high catalytic activities for the reaction of sterically hindered ketones (including di-tertbutyl ketone) and triorganosi lanes such as Et(3)SiH and (t-Bu)Me(2)SiH. The catalyst from 1b showed no leaching of rhodium after reaction and was reusable without decrease of the activity.
  • Hirohisa Ohmiya, Yusuke Makida, Tatsunori Tanaka, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 130 (51) 17276 - + 0002-7863 2008/12 [Refereed][Not invited]
     
    Allyl-aryl coupling between allylic acetates and arylboronic acids took place in the presence of catalytic amounts of Pd(OAc)(2), 1,10-phenanthroline, and AgSbF(6) with high gamma-selectivity and EIZ-selectivity, The reaction of an optically active allylic acetates with an alpha-stereogenic center proceeded with excellent alpha-to-gamma chirality transfer with syn-selectivity and gave the corresponding optically active allyl-aryl coupling products with a stereogenic center at the benzylic position.
  • Hajime Ito, Yusuke Sasaki, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 130 (47) 15774 - + 0002-7863 2008/11 [Refereed][Not invited]
     
    A versatile synthetic method for the preparation of the allenylboronates, Cu(I)-catalyzed reaction of propargylic carbonates with a diboron, is described. A Cu(O-t-Bu)-Xantphos catalyst system was effective for the preparation of various allenylboron compounds, allenylboronates with different substitution patterns, those with functional groups, and an axially chiral one. The Lewis acid promoted stereoselective addition to aldehydes leading to homopropargylic alcohols showed the usefulness of the new allenylboronates.
  • Atsuko Ochida, Go Hamasaka, Yoshihiro Yamauchi, Soichiro Kawamorita, Naoya Oshima, Kenji Hara, Hirohisa Ohmiya, Masaya Sawamura
    ORGANOMETALLICS 27 (21) 5494 - 5503 0276-7333 2008/11 [Refereed][Not invited]
     
    Synthesis, properties, and catalytic applications of a caged trialkylphosphine ligand with Me(3)P-like steric and electronic characters, 4-phenyl-1-phospha-4-silabicyclo[2.2.2] octane (Ph-SMAP), are reported. Given a phenyl group at the silicon atom. the Ph-SMAP ligand displayed nonvolatility with retention of Me3P-like steric and electronic properties. The new ligand is air-stable, crystalline, and easy to handle. Single-crystal X-ray diffraction analyses of Ph-SMAP and its coordination compounds such as borane, rhodium(I), and Pt(II) complexes revealed a rigid, linear structural feature of the Ph-SMAP framework. DFT calculations [B3LYP/6-31G(d,p)] indicated that the electron-donating ability of Ph-SMAP is slightly stronger than that of Me(3)P and that replacement of Si atom of Ph-SMAP with a carbon atom drastically decreases the donor power. The Ph-SMAP ligand markedly accelerated the rhodium-catalyzed hydrosilylation and hydrogenation of ketones as compared with the effect of conventional phosphine ligands such as Me(3)P, Bu(3)P, (t-Bu)(3)P, and PPh(3), when it was used in combination with [{RhCl (C(2)H(4))(2)}(2)] and [Rh(OMe)(cod)], respectively, with P/Rh ratio of 1:1.
  • Hideto Ito, Yusuke Makida, Atsuko Ochida, Hirohisa Ohmiya, Masaya Sawamura
    ORGANIC LETTERS 10 (21) 5051 - 5054 1523-7060 2008/11 [Refereed][Not invited]
     
    A cationic gold(l) complex with a semihollow-shaped trialkynylphosphine catalyzed 5-exo-dig and 6-endo-dig cyclizations of various internal alkynic beta-keto esters, showing a marked advantage over a gold(I)-PPh(3) complex with respect to the rates of the reactions and the product yields. It is proposed that the gold-bound alkynic substrate in a catalytic pocket must be somewhat folded and that such a steric effect makes the carbon-carbon bond formation entropically more favorable.
  • Yohsuke Asano, Hajime Ito, Kenji Hara, Masaya Sawamura
    ORGANOMETALLICS 27 (22) 5984 - 5996 0276-7333 2008/11 [Refereed][Not invited]
     
    The addition of terminal alkynes to aromatic aldehydes was carried out in t-BuOH under mild conditions in the presence of a Cu-phosphine complex, which was prepared in situ from Cu(O-t-Bu) and TRAP chiral bisphosphine, to yield enantiomerically enriched propargyl alcohols with moderate enantioselectivities. Studies on the screening of various ligands showed that wide bite angles of bisphosphine ligands are important for the Cu catalysis. According to the analysis of stoichiometric reactions, the reaction presumably involves the nucleophilic addition of a TRAP-coordinated Cu(I) acetylide to an aldehyde: The alcoholic solvent participates in the addition through coordination to the Cu center and simultaneous protonation of the carbonyl oxygen. The C-C bond-forming addition step is reversible with a strong preference for the backward reaction.
  • Soichiro Kawamorita, Go Hamasaka, Hirohisa Ohmiya, Kenji Hara, Atsushi Fukuoka, Masaya Sawamura
    ORGANIC LETTERS 10 (20) 4697 - 4700 1523-7060 2008/10 [Refereed][Not invited]
     
    A heterogeneous mono(phosphine)-Rh catalyst system silica-SMAP-Rh(OMe)(cod), where silica-SMAP stands for a caged, compact trialkylphosphine (SMAP) supported on silica gel, showed broad applicability toward the hydrogenation of hindered ketones. Doubly a-branched ketones such as diisopropyl ketone was hydrogenated under nearly atmospheric conditions. Di-tert-butyl ketone could be hydrogenated under more forcing conditions.
  • Manabu Kiguchi, Shinichi Miura, Takuya Takahashi, Kenji Hara, Masaya Sawamura, Kei Murakoshi
    JOURNAL OF PHYSICAL CHEMISTRY C 112 (35) 13349 - 13352 1932-7447 2008/09 [Refereed][Not invited]
     
    We investigated the single 1,4-benzenediamine molecule bridging between Au or Pt electrodes. The conductances of the molecular junctions with the Au-NH2 and Pt-NH2 bonds (Au-NH2 and Pt-NH2 molecular junctions) were 1 x 10(-1) Go (2e(2)/h) and 5 x 10(-3) G(0), respectively. The stretching lengths of the Au-NH2 and Pt-NH2 molecular junctions were 0.03 and 0.07 nm, respectively. The conductance value of the Au-NH2 molecular junction was unexpectedly larger than the value evaluated with the density of states of the metal electrodes and the molecule-metal bond strength, which have been discussed before. The large conductance value could be explained by the small energy difference between metal and molecular orbitals (Delta E) and the high degree of pi-conjugation (P) of the Au-NH2 molecular junction, which would be unique characteristics of the Au-NH2 bond. The present Study showed the importance of these two factors (Delta E, P) in studying the conductance of the single molecualr junction.
  • Hajime Ito, Tomohisa Saito, Naoya Oshima, Noboru Kitamura, Shoji Ishizaka, Yukio Hinatsu, Makoto Wakeshima, Masako Kato, Kiyoshi Tsuge, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 130 (31) 10044 - + 0002-7863 2008/08 [Refereed][Not invited]
     
    Reversible mechanotronic luminescence of [(C(6)F(5)Au)(2)(mu-1,4-diisocyanobenzene)] is reported. Grinding of the complex induced a photoluminescent color change, which was restored by exposure to a solvent. This cycle was repeated 20 times with no color degradation in the emissions. Their optical properties, X-ray crystallographic analysis, IR, and XRD measurements strongly suggested that the change in the molecular arrangement is responsible for this mechanochromic property. Intermolecular aurophilic bondings presumably play a key role in the altered emission.
  • Yutaka Matsuo, Yoichiro Kuninobu, Ayako Muramatsu, Masaya Sawamura, Eiichi Nakamura
    ORGANOMETALLICS 27 (14) 3403 - 3409 0276-7333 2008/07 [Refereed][Not invited]
     
    K(C60R5) (1, R = Me, Ph) was generated by deprotonation Of C60R5H (2) and allowed to react with N-fluoropyridinium triflate and N-chloro- and N-bromosuccinimide in benzene at 25 degrees C for 10 min to obtain halogenated fullerenes C60R5X (3a: R = Me, X = F; 3b: R = Me, X = Cl; 3c: R = Me, X = Br; 4a: R = Ph, X = F; 4b: R = Ph, X = Cl, 4c: R = Ph, X = Br) in good yield. The pentamethyl[60]fullerene halides are useful for the synthesis of a variety of eta(5)-fullerene metal complexes. The reaction of the fullerene bromide 3c with the low-valent transition metal complexes Na[Re(CO)(4)] Fe(CO)(5), Ru-3(CO)(12), and Na[Co(Co)(4)] gave Re(eta(5)-C60Me5)(CO3) (5), Fe(eta(5)-C60Me5)Br(CO)(2) (6), Ru(eta(5)-C60Me5)Br(CO)(2) (7), and CO(eta(5)-C60Me5)(CO)(2) (8), respectively. The structures of halide 3c and rhenium complex 5 were determined by X-ray crystallography. Electrochemical measurements on A and 3c were also performed. The iron complex 6 was converted into Fe(eta(5)-C60Me5)C-P (9), Fe(eta(5)-C60Me5)Me(CO)(2) (10), Fe(eta(5)-C60Me5)(CO)(2)(CCH) (11), and Fe(eta(5)-C60Me5)CO)(2)(CCPh) (12), by ligand exchange reactions.
  • Hajime Ito, Shinichiro Ito, Yusuke Sasaki, Kou Matsuura, Masaya Sawamura
    PURE AND APPLIED CHEMISTRY 80 (5) 1039 - 1045 0033-4545 2008/05 [Refereed][Not invited]
     
    Copper-catalyzed gamma-selective substitution of allylic carbonates with diboron provides a new method for the efficient synthesis of allylboronates. Optically active a-chiral allylboronates were synthesized through the reaction of chiral allylic carbonates with bis(pinacolato)diboron in the presence of achiral Cu(I)-catalyst with highly efficient chirality transfer. Additionally, in the presence of a chiral Cu(I) catalyst, optically active alpha-chiral allylboronates were obtained with >90 % ee through the reaction of prochiral substrates with the diboron.
  • Kenji Hara, Ryuto Akiyama, Satoru Takakusagi, Kohei Uosaki, Toru Yoshino, Hiroyuki Kagi, Masaya Sawamura
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 47 (30) 5627 - 5630 1433-7851 2008 [Refereed][Not invited]
  • Hajime Ito, Yuki Kosaka, Kousuke Nonoyama, Yusuke Sasaki, Masaya Sawamura
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 47 (39) 7424 - 7427 1433-7851 2008 [Refereed][Not invited]
  • Hajime Ito, Shinichiro Ito, Yusuke Sasaki, Kou Matsuura, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 129 (48) 14856 - + 0002-7863 2007/12 [Refereed][Not invited]
     
    A method for the synthesis of alpha-chiral allylboronates featuring the Cu(I)-catalyzed enantioselective substitution of readily available allylic carbonates with a diboron is described. Using this method, various alpha-chiral allylboronates, including functionalized allylboronates, were successfully synthesized, with high enantiomeric purity.
  • Kenji Hara, Keiji Iwahashi, Satoru Takakusagi, Kohei Uosaki, Masaya Sawamura
    SURFACE SCIENCE 601 (22) 5127 - 5132 0039-6028 2007/11 [Refereed][Not invited]
     
    Functionalization of self-assembled monolayer (SAM) of alkanethiolate with metal containing unit is one of the versatile methods to obtain functional surfaces such as heterogeneous catalysts. However, organic molecules that strongly bind to transition metals at SAM terminal are limited. Recently N-heterocyclic carbenes (NHCs) such as cyclic diaminocarbenes have emerged as strongly a-donating ligands forming a robust bond with broad spectrum of transition metals. In the present study, for the purpose of establishment of a new robust basement for heterogeneous metal catalysts, a SAM of the alkanethiolate terminated with NHC-rhodium(I) complex moiety was prepared by utilizing a newly designed disulfide molecule bearing NHC-metal complex terminals. X-ray photoelectron spectroscopy (XPS) analysis and angle resolved XPS measurement revealed successful formation of the Rh-complex-terminated SAM on a gold substrate. Infrared reflection absorption spectroscopy (IRRAS) analysis suggested that the linker methylene chains connecting the rhodium complex moiety and the gold surface are in a loosely packed structure. This unique chemical species, NHC, would be a promising candidate as a basement for the construction of functional surface. (C) 2007 Elsevier B.V. All rights reserved.
  • Hajime Ito, Tsuyoshi Maeda, Masaya Sawamura
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 80 (10) 1981 - 1986 0009-2673 2007/10 [Refereed][Not invited]
     
    A new tetranuclear platinum(II) metallamacrocycle, including four 1,3-diisocyanoarene ligands, was synthesized and characterized. The reaction Of PtI2(cod) with an equimolar amount of the 1,3-diisocyanoarene ligand in dichloromethane under diluted conditions gave the metallamacrocycle [(PtI2)(4)(1,3-diisocyanoarene)(4)], X-ray crystallographic analysis showed that the complex adopted a square ring structure with trans arrangement of coordinated isocyanides around the Pt atoms. GPC, ESI-MS, IR, and NMR analysis of the metallamacrocycle showed that the tetranuclear macrocyclic scaffold was maintained in solution.
  • Yohsuke Asano, Kenji Hara, Hajime Ito, Masaya Sawamura
    ORGANIC LETTERS 9 (20) 3901 - 3904 1523-7060 2007/09 [Refereed][Not invited]
     
    The addition of terminal alkynes to aromatic aldehydes was carried out under mild conditions in the presence of a Cu-phosphine complex, which was prepared in situ from Cu(O-t-Bu) and TRAP chiral bisphosphine, to yield enantiomerically enriched propargyl alcohols with moderate enantioselectivities. Furthermore, according to stoichiometric reactions, the reaction presumably involves the addition of a TRAP-coordinated Cu(l) acetylide to an aldehyde.
  • Manabu Kiguchi, Shinichi Miura, Kenji Hara, Masaya Sawamura, Kei Murakoshi
    APPLIED PHYSICS LETTERS 91 (5) 0003-6951 2007/07 [Refereed][Not invited]
     
    The authors have studied the conductance of a 1,4-disubstituted isocyanide(-NC) or thiol(-SH) benzene molecule anchored to two Pt electrodes. A single molecular junction showing a well-defined conductance value (similar to 3x10(-2)G(0), G(0)=2e(2)/h) was fabricated with the Pt electrodes. The conductance of the molecular junction was one order higher than the previously documented value using Au electrodes. These observations could be explained by differences in the local density of states of the contact metal atom at the Fermi level and the extent of the hybridization and energy difference between the molecular and metal orbitals. Further insight into the binding strengths of the metal-anchoring group bond was obtained by statistically analyzing the stretching length of the molecular junction. (c) 2007 American Institute of Physics.
  • Atsuko Ochida, Masaya Sawamura
    CHEMISTRY-AN ASIAN JOURNAL 2 (5) 609 - 618 1861-4728 2007 [Refereed][Not invited]
     
    Trialkynylphosphines substituted with bulky triarylsilyl groups at the alkyne termini were synthesized. The new phosphines P(C equivalent to CSiAr3,)3 (Ar = 3,5-tBu(2)-4-MeOC6H2, 3,5-(Me3Si)(2)C6H3) are uncrowded near the phosphorus atom but bulky in the distal region. As a result, they contain a large cavity, at the bottom of which the phosphine lone-pair electrons are located. The compounds are stable to oxidation by air and hydrolysis. DFT calculations suggested that the triethynylphosphines are good pi-acceptor ligands, comparable with P(OAr)(3). ne trialkynylphosphines reacted with [{RhCl(cod)}(2)] (P/Rh = 1.1:1) to give selectively the monophosphine-rhodium complex [RhCl(cod)P(C CSiAr3)(3)]. X-ray crystal-structure analysis revealed that the {RhCl(cod)} fragment is fully accommodated by the cavity of the phosphine ligand. Compared to the effect of analogues with smaller end caps and PPh3, the trialkynylphosphines accelerated markedly the rhodium-catalyzed hydrosilylation of ketones with a trioganosilane. It is proposed that the higher catalytic activity observed with the holey phosphines is a result of the preferential formation of a monophosphine-rhodium species.
  • Go Hamasaka, Atsuko Ochida, Kenji Hara, Masaya Sawamura
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 46 (28) 5381 - 5383 1433-7851 2007 [Refereed][Not invited]
  • Kenji Hara, Shinobu Tayama, Hidekazu Kano, Takuya Masuda, Satoru Takakusagi, Toshihiro Kondo, Kohei Uosaki, Masaya Sawamura
    CHEMICAL COMMUNICATIONS (41) 4280 - 4282 1359-7345 2007 [Refereed][Not invited]
     
    A single-crystal silicon surface was modified with a bisoxazoline-Pd molecular layer and utilized as a highly efficient (catalyst turnover number up to 780 000, 110 degrees C, 72 h) and recyclable catalyst in the aerobic oxidation of benzylic alcohols.
  • Hajime Ito, Takayuki Kato, Masaya Sawamura
    CHEMISTRY-AN ASIAN JOURNAL 2 (11) 1436 - 1446 1861-4728 2007 [Refereed][Not invited]
     
    New isocyanide ligands with meta-terphenyl backbones were synthesized. 2,6-Bis[3,5-bis(trimethylsilyl)-phenyl]-4-methylphenyl isocyanide exhibited the highest rate acceleration in rhodium-catalyzed hydrosilylation among other isocyanide and phosphine ligands tested in this study. H-1 NMR spectroscopic studies on the coordination behavior of the new ligands to [Rh(cod)(2)]BF4 indicated that 2,6-bis-[3,5-bis(trimethylsilyl)phenyl]-4-methylphenyl isocyanide exclusively forms the biscoordinated rhodium-isocyanide complex, whereas less sterically demanding isocyanide ligands predominantly form tetracoordinated rhodium-isocyanide complexes. FTIR and C-13 NMR spectroscopic studies on the hydrosilylation reaction mixture with the rhodium-isocyanide catalyst showed that the major catalytic species responsible for the hydrosilylation activity is the Rh complex coordinated with the isocyanide ligand. DFT calculations of model compounds revealed the higher affinity of isocyanides for rhodium relative to phosphines. The combined effect of high ligand affinity for the rhodium atom and the bulkiness of the ligand, which facilitates the formation of a catalytically active, monoisocyanide-rhodium species, is proposed to account for the catalytic efficiency of the rhodium-bulky isocyanide system in hydrosilylation.
  • Atsuko Ochida, Hideto Ito, Masaya Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 128 (51) 16486 - 16487 0002-7863 2006/12 [Refereed][Not invited]
  • Kenji Hara, Yoshikazu Kanamori, Masaya Sawamura
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 79 (11) 1781 - 1786 0009-2673 2006/11 [Refereed][Not invited]
     
    Palladium complexes with an imidazol-2-ylidene ligand functionalized with ester groups at its 4,5-positions were synthesized from a readily available imidazole derivative. or-Donation from the carbene ligand to the palladium atom is considerably weakened by functionalization with the two ester moieties.
  • Manabu Kiguchi, Shinichi Miura, Kenji Hara, Masaya Sawamura, Kei Murakoshi
    APPLIED PHYSICS LETTERS 89 (21) 0003-6951 2006/11 [Refereed][Not invited]
     
    The effect of anchoring group on the electrical conductance of a single molecule bridging two Au electrodes was studied using disubstituted [isocyanide (CN-), thiol (S-), or cyanide (NC-)] benzene. The conductance of a single Au/1,4-diisocyanobenzene/Au junction anchored by isocyanide via a C atom (junction with the Au-CN bond) was 3x10(-3)G(0)(=2e(2)/h). The value was comparable to 4x10(-3)G(0) of a single Au/1,4-benzenedithiol/Au junction with the Au-S bond. The Au/1,4-dicyanobenzene/Au molecular junction with the Au-NC bond did not show well-defined conductance values. The metal-molecule bond strength was estimated by the distance over which the molecular junction was stretched before breakdown. The stretched length of the molecular junction with the Au-CN bond was comparable to that of the Au junction, indicating that the Au-CN bond was stronger than the Au-Au bond. (c) 2006 American Institute of Physics.
  • Hajime Ito, Takayuki Kato, Masaya Sawamura
    CHEMISTRY LETTERS 35 (9) 1038 - 1039 0366-7022 2006/09 [Refereed][Not invited]
     
    Bulky isocyanide ligands having meta-terphenyl backbone were developed. Their usefulness as a supporting ligand in catalysis was illustrated by the application to the rhodium-catalyzed hydrosilylation of cyclohexanone. The combined effect of the high ligand affinity to the rhodium atom and the ligand bulkiness to facilitate the formation of a catalytically active, monoligated isocyanide-rhodium species was proposed.
  • Kenji Hara, Keiji Iwahashi, Yoshikazu Kanamori, Satoshi Naito, Satoru Takakusagi, Kohei Uosaki, Masaya Sawamura
    CHEMISTRY LETTERS 35 (8) 870 - 871 0366-7022 2006/08 [Refereed][Not invited]
     
    A dimeric N-heterocyclic carbene (NHC)-rhodium(I) complex connected with a long chain dialkyl disulfide linker was synthesized, and used for the preparation of a Rh-modified alkane thiolate monolayer on a gold surface.
  • A Ochida, S Ito, T Miyahara, H Ito, M Sawamura
    CHEMISTRY LETTERS 35 (3) 294 - 295 0366-7022 2006/03 [Refereed][Not invited]
     
    A series of silicon-constrained monodentate trialkylphosphines SMAPs bearing a Si substituent with diverse electronic natures were synthesized. DFT calculations and NMR measurements indicated that these compounds constitute a class of electronically tunable trialkylphosphines. The tunable range of donor power overlaps those of tri(tert-butyl)phosphiiie and monoalkyldiarylphosphines.
  • Synthesis and properties of SMAPs 1-phospha-4-silabicyclo[2.2.2]octane derivatives
    Atsuko Ochida, Masaya Sawamura
    ARKIVOC 359 - 369 1424-6376 2006 [Refereed][Not invited]
     
    Synthesis and properties of a new class of trialkylphosphine ligands SMAPs (1-phospha-4-silabicyclo[ 2.2.2] octane derivatives, named after silicon-constrained monodentate alkylphosphine) with Me3P-like steric demand around the phosphorus center are described. A new feature of this class of ligands is the presence of a site for functionalization at the backside of the P-lone pair, which is not the case for Me3P. The SMAP ligands contain phosphorus and silicon atoms at each bridgehead of the bicyclo[ 2.2.2] octane framework. The molecular constraint of the bicyclic framework makes the steric demand around the phosphorus center as small as that of Me3P and projects the P-lone pair and the Si-substituent ( R) in diametrically opposite directions on the straight line defined by the two bridgehead atoms. SMAP derivatives bearing Si substituents with varied electronic natures are obtainable by transforming the parent compound 4-phenyl-phospha-4-silabicyclo[ 2.2.2] octane (Ph-SMAP) through Si - Ph bond cleavage, and they constitute a class of electronically tunable trialkylphosphines. DFT calculations indicated that the parent ligand Ph-SMAP is similar to Me3P in donor power and that the tunable range of the donor power overlaps those of (t-Bu)(3)P and RAr2P ( R: alkyl, Ar: aryl).
  • K Hara, R Akiyama, M Sawamura
    ORGANIC LETTERS 7 (25) 5621 - 5623 1523-7060 2005/12 [Refereed][Not invited]
     
    [GRAPHICS] A toluene-coordinated silyl borate, [Et3Si(toluene)]B(C6F5)(4), demonstrated catalytic activities significantly higher than those of Me3SiOTf and Me3SiNTf2 in Mukaiyama aldol and Diels-Alder reactions.
  • H Ito, C Kawakami, M Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 127 (46) 16034 - 16035 0002-7863 2005/11 [Refereed][Not invited]
  • H Ito, K Takagi, T Miyahara, M Sawamura
    ORGANIC LETTERS 7 (14) 3001 - 3004 1523-7060 2005/07 [Refereed][Not invited]
     
    A gold(I) complex of Xantphos AuCl(xantphos) catalyzes the dehydrogenative silylation of alcohols with high chemoselectivity and solvent tolerance. It is selective for the silylation of hydroxyl groups in the presence of alkenes, alkynes, alkyl halides (RCl, RBr), ketones, aldehydes, conjugated enones, esters, and carbamates.
  • H Ito, A Watanabe, M Sawamura
    ORGANIC LETTERS 7 (9) 1869 - 1871 1523-7060 2005/04 [Refereed][Not invited]
     
    Cu(I) complexes of xanthane-based diphosphines were versatile catalysts for dehydrogenative alcohol silylation, exhibiting high activity and broad substrate scope. Highly selective silylation of 1-decanol over 2-decanol is possible even with a silylating reagent of small steric demand such as HSiMe2Ph or HSiEt3.
  • C Burger, JC Hao, QC Ying, H Isobe, M Sawamura, E Nakamura, B Chu
    JOURNAL OF COLLOID AND INTERFACE SCIENCE 275 (2) 632 - 641 0021-9797 2004/07 [Refereed][Not invited]
     
    The self-assembly behavior of a fullerene-based surfactant, C-60(CH3)(5)K, in water was studied using a combination of static and dynamic light scattering, as well as transmission electron microscopy, and compared to that of the compound C-60(C6H5)(5)K. Both fullerene surfactant systems spontaneously assemble into large vesicles consisting of closed spherical shells formed by bilayers, with critical aggregation concentrations (CAC) lower than 10(-6) g ml(-1). At low concentrations, the aggregate sizes Of C-60(CH3)(5)K (radius R similar to 26.8 nm) and C-60(C6H5)(5)K (R similar to 17.0 nm) were found to be substantially different from each other, showing that the change of the substituents surrounding the polar cyclopentadienide head group makes it possible to control the size of the resulting aggregates. Furthermore, the C-60(CH3)(5)K vesicles were found to exist in two qualitatively different types of aggregation with a critical reaggregation concentration (CRC) located at 3.30 x 10(-6) g ml(-1). Above the CRC, larger aggregates were observed (R similar to 37.6 nm), showing a more complex form of supramolecular aggregation, e.g., in terms of multi-bilayer vesicles and/or of clusters of bilayer vesicles. (C) 2004 Elsevier Inc. All rights reserved.
  • C Burger, JC Hao, QC Ying, H Isobe, M Sawamura, E Nakamura, B Chu
    JOURNAL OF COLLOID AND INTERFACE SCIENCE 275 (2) 632 - 641 0021-9797 2004/07 [Not refereed][Not invited]
     
    The self-assembly behavior of a fullerene-based surfactant, C-60(CH3)(5)K, in water was studied using a combination of static and dynamic light scattering, as well as transmission electron microscopy, and compared to that of the compound C-60(C6H5)(5)K. Both fullerene surfactant systems spontaneously assemble into large vesicles consisting of closed spherical shells formed by bilayers, with critical aggregation concentrations (CAC) lower than 10(-6) g ml(-1). At low concentrations, the aggregate sizes Of C-60(CH3)(5)K (radius R similar to 26.8 nm) and C-60(C6H5)(5)K (R similar to 17.0 nm) were found to be substantially different from each other, showing that the change of the substituents surrounding the polar cyclopentadienide head group makes it possible to control the size of the resulting aggregates. Furthermore, the C-60(CH3)(5)K vesicles were found to exist in two qualitatively different types of aggregation with a critical reaggregation concentration (CRC) located at 3.30 x 10(-6) g ml(-1). Above the CRC, larger aggregates were observed (R similar to 37.6 nm), showing a more complex form of supramolecular aggregation, e.g., in terms of multi-bilayer vesicles and/or of clusters of bilayer vesicles. (C) 2004 Elsevier Inc. All rights reserved.
  • Y Matsuo, K Tahara, M Sawamura, E Nakamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 126 (28) 8725 - 8734 0002-7863 2004/07 [Refereed][Not invited]
     
    Selective penta-addition of a methylcopper reagent followed by addition of a phenylcopper reagent to a suitably modified synthetic intermediate results in creation of 40pi-electron systems-hoop- and bowl-shaped cyclic benzenoid compounds, [10]cyclophenacene, and dibenzo-fused corannulene derivatives. The 40pi-electron cyclophenacene derivatives have been found to be chemically stable, yellow-colored, luminescent (560 nm), and EPR-silent. X-ray crystallographic analysis provided precision structural data sets. The dibenzo-fused corannulene derivatives exhibit blue-green (460 nm) to red (649 nm) fluorescence.
  • Y Kuninobu, Y Matsuo, M Toganoh, M Sawamura, E Nakamura
    ORGANOMETALLICS 23 (13) 3259 - 3266 0276-7333 2004/06 [Refereed][Not invited]
     
    The nickel-, palladium-, and platinum-RFCp complexes Ni(eta(5)-RFCp)(eta(3)-allylic) (3b, RFCp = C60R5, R = Me, allylic = methallyl; 4a, R = Ph, allylic = allyl; 4b, R = Ph, allylic = methallyl), Pd(eta(5)-RFCp)(eta(3)-allylic) (7a, R = Me, allylic = allyl; 7b, R Me, allylic = methallyl; 7c, R Me, allylic = crotyl; 8a, R = Ph, allylic = allyl; 8b, R Ph, allylic = methallyl; 8c, R Ph, allylic = crotyl), and Pt(eta(5)-RFCp)(eta(3)-methallyl) (9, R = Me; 10, R = Ph), were synthesized by transmetalation between K(RFCp) (R = Me, Ph) and [Ni(allylic)Br](2), [Pd(allylic)Cl](2), or [Pt(methallyl)Cl](2) in THF at 25 degreesC for 10 min: The nickel-PhFCp complexes 4a,b are unusually more stable toward molecular oxygen than the corresponding simple nickel cyclopentadienides and survive in air for many hours at elevated temperature. The crystal structures and the electrochemical properties of the palladium complexes suggest that the unusual stability of the PhFCp complexes is due to the kinetic stabilization effect of the five Ph groups surrounding the metal atom and the thermodynamic stabilization effect of the electron-withdrawing fullerene moiety, hence suggesting new opportunities for the synthesis of otherwise unstable organometallic compounds.
  • Nickel, Palladium and Platinum Complex of ŋ5-Cyclopentadienide C60R5 Ligands. Kinetic and Thermodynamic Stabilization Effects of C60Ph5 Ligand.
    Organometallics 231, 3259-3266 2004 [Not refereed][Not invited]
  • A Ochida, K Hara, H Ito, M Sawamura
    ORGANIC LETTERS 5 (15) 2671 - 2674 1523-7060 2003/07 [Refereed][Not invited]
     
    [GRAPHICS] A new trialkylphosphine ligand with Me3P-like steric and electronic properties, 4-phenyl-1-phospha-4-silabicyclo[2.2.2]octane (Ph-SMAP), was synthesized. Given a phenyl group at the silicon atom, the Ph-SMAP ligand displayed nonvolatility with retention of Me3P-like properties. The new ligand was air-stable, crystalline, and easy to handle.
  • E Nakamura, K Tahara, Y Matsuo, M Sawamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 125 (10) 2834 - 2835 0002-7863 2003/03 [Refereed][Not invited]
  • M Toganoh, K Suzuki, R Udagawa, A Hirai, M Sawamura, E Nakamura
    ORGANIC & BIOMOLECULAR CHEMISTRY 1 (14) 2604 - 2611 1477-0520 2003 [Refereed][Not invited]
     
    Treatment of a 1,7-diorgano[60]fullerene with Grignard reagents or organocopper reagents affords a [60]fullerene indenide or a [60]fullerene cyclopentadienide regioselectively in good to excellent yields. These reactions gave an insight into the reaction mechanism of the organocopper penta-addition reaction of [60]fullerene, giving [60]fullerene cyclopentadienide in quantitative yield.
  • M Sawamura, K Kawai, Y Matsuo, K Kanie, T Kato, E Nakamura
    NATURE 419 (6908) 702 - 705 0028-0836 2002/10 [Refereed][Not invited]
     
    Polar liquid crystalline materials can be used in optical and electronic applications, and recent interest has turned to formation strategies that exploit the shape of polar molecules and their interactions to direct molecular alignment(1,2). For example, banana-shaped molecules align their molecular bent within smectic layers(3), whereas conical molecules should form polar columnar assemblies(4-9). However, the flatness of the conical molecules used until now(4-6,9) and their ability to flip(7,8) have limited the success of this approach to making polar liquid crystalline materials. Here we show that the attachment of five aromatic groups to one pentagon of a C-60 fullerene molecule yields deeply conical molecules that stack into polar columnar assemblies. The stacking is driven by attractive interactions between the spherical fullerene moiety and the hollow cone formed by the five aromatic side groups of a neighbouring molecule in the same column. This packing pattern is maintained when we extend the aromatic groups by attaching flexible aliphatic chains, which yields compounds with thermotropic and lyotropic liquid crystalline properties. In contrast, the previously reported fullerene-containing liquid crystals(10-17) all exhibit thermotropic properties only, and none of them contains the fullerene moiety as a functional part of its mesogen units. Our design strategy should be applicable to other molecules and yield a range of new polar liquid crystalline materials.
  • M Sawamura, N Nagahama, M Toganoh, E Nakamura
    JOURNAL OF ORGANOMETALLIC CHEMISTRY 652 (1-2) 31 - 35 0022-328X 2002/06 [Refereed][Not invited]
     
    We have found the conditions to achieve penta-addition of an alkenyl group to [60]fullerene in good yield with the aid of an RCu-type reagent prepared from the corresponding alkenyllithium reagent. The addition took place regioselectively at the five double bonds surrounding a pentagon in the fullerene and with retention of the stereochemistry of the alkenylcopper reagent. The reaction thus produced a cyclopentadiene embedded in the fullerene core that bears five 1-alkenyl groups (1c-e). (C) 2002 Published by Elsevier Science B,V.
  • SAWAMURA M, KUNINOBU Y, TOGANOH M, MATSUO Y, YAMANAKA M, NAKAMURA E
    J.Am.Chem.Soc. 124 (32) 9354 - 9355 0002-7863 2002 [Not refereed][Not invited]
  • M Sawamura, M Toganoh, H Iikura, Y Matsuo, A Hirai, E Nakamura
    JOURNAL OF MATERIALS CHEMISTRY 12 (7) 2109 - 2115 0959-9428 2002 [Refereed][Not invited]
     
    A variety of [70]fullerene derivatives bearing three organic groups C70R3H (1, R = aryl, methyl) have been synthesized in 90-99% isolated yield by the reaction of [70]fullerene with a Grignard reagent in the presence of CuBr.S(CH3)(2). Deprotonation of C70R3H with a metal alkoxide gave the corresponding metal complex M(eta(5)-C70R3) [M = K (2), Tl (3)]. X-ray crystallographic analysis as well as theoretical study revealed the nature of the 68pi-electron ligand, C70R3-.
  • SQ Zhou, C Burger, B Chu, M Sawamura, N Nagahama, M Toganoh, UE Hackler, H Isobe, E Nakamura
    SCIENCE 291 (5510) 1944 - 1947 0036-8075 2001/03 [Refereed][Not invited]
     
    The low solubility of fullerenes in aqueous solution Limits their applications in biology. By appropriate substitution, the fullerenes can be transformed into stabilized anions that are water soluble and can form targe aggregated structures. A Laser light scattering study of the association behavior of the potassium salt of pentaphenyl fullerene (Ph5C60K) in water revealed that the hydrocarbon anions Ph5C60- associate into bilayers, forming stable spherical vesicles with an average hydrodynamic radius and a radius of gyration of about 17 nanometers at a very Low critical aggregation concentration of Less than 10(-7) moles per Liter. The average aggregation number of associated particles in these large spherical Vesicles is about 1.2 x 10(4).
  • E Nakamura, M Sawamura
    PURE AND APPLIED CHEMISTRY 73 (2) 355 - 359 0033-4545 2001/02 [Refereed][Not invited]
     
    Treatment of [60]fullerene with an organocopper reagent converts one of the pen tagons of the fullerene into cyclopentadienyl anion through addition of five organic groups on every peripheral carbon atom surrounding the pentagon. Similar treatment of [70]fullerene afforded indenyl anion through regioselective tri-addition of the organic group. These anionic moieties strongly interact with the remainder of the fullerene pi -system, and provide unique opportunity for exploration of organometallic chemistry of a new class of metal cyclopentadienides.
  • App. Phys. Lett. 90(1), 209-212 2001 [Not refereed][Not invited]
  • M Sawamura, Y Kuninobu, E Nakamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 122 (49) 12407 - 12408 0002-7863 2000/12 [Refereed][Not invited]
  • R Kuwano, M Sawamura, Y Ito
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 73 (11) 2571 - 2578 0009-2673 2000/11 [Refereed][Not invited]
     
    The catalytic asymmetric hydrogenation of alpha-(acetamido)acrylates was carried out with the rhodium complexes prepared from [Rh(cod)(2)]BF4 and trans-chelating chiral bisphosphine ligands, (S,S)-2,2'-bis[(R)-1-(dialkylphosphino)ethyl]-1,1'-biferrocenes [(R,R)-(S,S)-TRAPs]. In the reaction of beta -unsubstituted or beta -monosubstituted alpha-(acetamido)acrylates [(E)-RCH=C(NHAc)CO2Me], the selectivity for (R)-hydrogenation product increased with decreasing steric demand of the substrate beta -substituent and the ligand P-substituent as well as decreasing hydrogen pressure. The selectivity for the (R)-product in the reaction with EtTRAP-rhodium catalyst at 60 degreesC and 0.5 kg cm(-2) of hydrogen pressure was as follows: R = H, 96% ee; R = Me, 92% ee; R = Ph, 77% ee; R = i-Pr, 57% ee. The remarkable steric and pressure effects caused a dramatic reversal of enantioselectivity in the reaction of methyl 2-(N-acetylamino)cinnamate (R = Ph). For example, the selectivity of 87% (R) with EtTRAP at 60 degreesC and 0.1 kg cm(-2) of hydrogen pressure has reversed to 92% (S) with i-B uTRAP at 15 degreesC and atmospheric hydrogen pressure. Hydrogenation of the beta,beta -disubstituted alpha-(acetamido) acrylates proceeded smoothly at 15 degreesC and atmospheric hydrogen pressure with high enantioselectivity in favor of the 2S-isomers when EtTRAP or BuTRAP was employed as the chiral ligand.
  • H Sawamura, H Hamashima, Y Ito
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 73 (11) 2559 - 2562 0009-2673 2000/11 [Not refereed][Not invited]
     
    Asymmetric Michael addition of diethyl (1-cyanoethyl)phosphonate with vinyl ketones or acrylaldehyde in the presence of 0.01 molar amount of a rhodium catalyst prepared in situ from Rh(acac)(CO)(2) and a trans-chelating chiral diphosphine ligand (R,R)-(S,S)-2,2"-bis[1-(diphenylphosphino)ethyl]-1,1"-biferrocene (PhTRAP) in benzene at 3 degreesC gave optically active phosphonates having a phosphorus-substituted quaternary asymmetric carbon center with high enantiomeric excesses (92-93% ee) in high yields. The Michael addition product from acrylaldehyde was converted into an optically active (1-aminoalkyl)phosphonic acid derivative.
  • M Sawamura, N Nagahama, M Toganoh, UE Hackler, H Isobe, E Nakamura, SQ Zhou, B Chu
    CHEMISTRY LETTERS (9) 1098 - 1099 0366-7022 2000/09 [Refereed][Not invited]
     
    A new class of hydrocarbon anions, pentaaryl- and penta-methylfullerene anions R5C60- (R = Ph, 4-BuC6H4, 4-PhC6H4, Me) was found to be stable and soluble in water. Atomic force microscopic observation and dynamic light scattering measurements indicated that the potassium salt Ph5C60K in water forms spherical aggregates with an averaged radius of about 17 nm.
  • M Sawamura, M Toganoh, K Suzuki, A Hirai, H Iikura, E Nakamura
    ORGANIC LETTERS 2 (13) 1919 - 1921 1523-7060 2000/06 [Refereed][Not invited]
     
    Fullerene cyclopentadienide (PhCH2)(2)Ph3C60- and indenide (PhCH2)(2)PhC60-, each bearing two different organic groups, were efficiently synthesized through regioselective reactions of 1,4-(PhCH2)(2)C-60 with an organocopper reagent (PhMgBr/CuBr . SMe2) or a Grignard reagent (PhMgBr) followed by deprotonation with (KOBu)-Bu-t.
  • M Sawamura, H Iikura, T Ohama, UE Hackler, E Nakamura
    JOURNAL OF ORGANOMETALLIC CHEMISTRY 599 (1) 32 - 36 0022-328X 2000/04 [Refereed][Not invited]
     
    The reaction of an organocopper reagent (ArMgBrlCuBr . SMe2) with C-60 was optimized for the fivefold addition forming a novel Cp-type ligand precursor 1,4,11,15,30-pentaaryl-2-hydro[60]fullerene (C60Ar5H, 1), where Ar stands for Ph, 4-CF3C6H4, 4-MeOC6H4, 4-ClC6H4, 4-BuC6H4, 4-PhC6H4, and 1-naphthyl groups. Under the optimized conditions, a large quantity (8.90 g) of C60Ph5H has been synthesized in a single operation. (C) 2000 Elsevier Science S.A. All rights reserved.
  • H Isobe, A Ohbayashi, M Sawamura, E Nakamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 122 (11) 2669 - 2670 0002-7863 2000/03 [Refereed][Not invited]
  • M Sawamura, M Toganoh, Y Kuninobu, S Kato, E Nakamura
    CHEMISTRY LETTERS (3) 270 - 271 0366-7022 2000/03 [Refereed][Not invited]
     
    Pentamethyl-monohydro[60] fullerene C60Me5H has been synthesized through five-fold addition of methylcopper reagent to C-60. The anion C60Me5- generated by deprotonation of C60Me5H forms organometallic complexes with K+ and TI+ ions with stronger metal-carbon interaction than that in the corresponding pentaphenylated ligand C60Ph5-.
  • R Kuwano, M Sawamura, J Shirai, M Takahashi, Y Ito
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 73 (2) 485 - 496 0009-2673 2000/02 [Refereed][Not invited]
     
    Asymmetric hydrosilylation of simple ketones with diphenylsilane proceeded at -40 degrees C in the presence of a rhodium complex (0.001-0.01 molar amount) coordinated with a trans-chelating chiral bisphosphine ligand bearing linear alkyl substituents on the phosphorus atoms, (R,R)-(S,S)-Et-, Pr-, or BuTRAP, giving the corresponding optically active (S)-econdary alcohols with up to 97% ee. The asymmetric hydrosilylation using TRAP ligands with bulkier P-substituents resulted in much lower enantioselectivities. The EtTRAP-rhodium catalyst was also effective for asymmetric hydrosilylation of keto esters with a coordination site for a rhodium atom (up to 98% ee) Optically active symmetrical diols were obtained with up to 99% ee from the corresponding diketones via the asymmetric reduction using 2.5 molar amounts of diphenylsilane.
  • M Murakami, R Minamida, K Itami, M Sawamura, Y Ito
    CHEMICAL COMMUNICATIONS (23) 2293 - 2294 1359-7345 2000 [Refereed][Not invited]
     
    A catalytic asymmetric [4 + 2] cycloaddition reaction of a vinylallene with buta-1,3-diene was developed in which a palladium complex modified by a ferrocene-derived chiral monophosphine ligand acted as a template transferring chirality to the product.
  • E Nakamura, H Isobe, N Tomita, M Sawamura, S Jinno, H Okayama
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 39 (23) 4254 - + 1433-7851 2000 [Refereed][Not invited]
  • H Isobe, M Sawamura, E Nakamura
    FULLERENE SCIENCE AND TECHNOLOGY 7 (4) 519 - 528 1064-122X 1999 [Refereed][Not invited]
     
    Optical resolution of chirally functionalized [60]fullerene has been achieved through formation of diastereomeric alpha-methoxyphenylacetic acid (MPA) esters. The diastereomeric ester products were easily separated either by open column silica gel chromatography or by high pressure liquid chromatography (HPLC) with BuckyPrep(R) column.
  • M Sawamura, H Iikura, A Hirai, E Nakamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 120 (32) 8285 - 8286 0002-7863 1998/08 [Refereed][Not invited]
  • H Iikura, S Mori, M Sawamura, E Nakamura
    JOURNAL OF ORGANIC CHEMISTRY 62 (23) 7912 - 7913 0022-3263 1997/11 [Refereed][Not invited]
  • R Kuwano, M Sawamura, S Okuda, T Asai, Y Ito, M Redon, A Krief
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 70 (11) 2807 - 2822 0009-2673 1997/11 [Refereed][Not invited]
     
    New chiral peralkyldiphosphines (S,S)-2,2 "-bis[(R)-1-(dialkylphosphino)ethyl]-1,1 "-biferrocenes ((R,R)-(S,S)-alkylTRAPs) were synthesized from (R)-N,N-dimethyl-1-ferrocenylethylamine in four steps in 38-68% overall yields (MeTRAP: 38%, EtTRAP: 68%, PrTRAP: 53%, BuTRAP: 56%, i-BuTRAP: 51%, i-PrTRAP: 42%). The reactions of alkylTRAP (Et-, Bu-, i-Bu, and i-PrTRAP) with 1 molar amount of PdBr2 gave trans-[PdBr2(alkylTRAP)] in good yields. The X-ray crystal structures of these palladium complexes revealed that alkylTRAPs coordinated to a palladium atom in a trans-chelating manner regardless of the P-alkyl substituents. The structures of palladium complexes of Et-, Bu-, and i-PrTRAP had nearly Ct-symmetry, but that of i-BuTRAP was deviated from Ct-symmetry significantly. AlkylTRAPs also reacted with [PtCl2(MeCN)(2)] and [RhCl(CO)(2)](2), giving the corresponding trans-chelate platinum and rhodium complexes. The crystal structure of trans-[RhCl(CO)(BuTRAP)] revealed that the conformation of the BuTRAP ligand in the complex was almost the same as that in the palladium complex trans-[PdBr2(BuTRAP)].
  • Conversion of alkyl halides into alcohols using a near stoichiometric amount of molecular oxygen: An efficient route to O-18- and O-17-labeled alcohols
    M Sawamura, Y Kawaguchi, E Nakamura
    SYNLETT (7) 801 - & 0936-5214 1997/07 [Refereed][Not invited]
     
    In the presence of near stoichiometric amount of molecular oxygen, various alkyl halides were converted to the corresponding alcohols in high yields through aerobic radical reaction promoted by a Bu-2(t-Bu)SnCl/NaBH3CN catalytic system. Isotope-labeled alcohols were prepared with O-18(2) and O-17(2) without loss of the isotopic purities of the starting oxygen gases.
  • H Isobe, H Tokuyama, M Sawamura, E Nakamura
    JOURNAL OF ORGANIC CHEMISTRY 62 (15) 5034 - 5041 0022-3263 1997/07 [Refereed][Not invited]
     
    For the purpose of doubly functionalizing fullerenes, new tris-annulating reagents 2(n) have been developed. The reagents carry, in one molecule, two cyclopropenone acetals which are connected with an n-carbon methylene tether. Upon thermolysis of 2(n) in the presence of C-60, the reagent undergoes [3 + 2] cycloaddition reaction twice in a regio- and stereoselective manner to give C-s and C-2 organofullerenes bearing two cyclopentenone acetals. The selectivity varies as the function of the tether structure. The experiments have shown that, in each series of different tether lengths, one can obtain one or two diastereomeric double adducts out of several structural possibilities. The selectivity of the reaction did not conform to the prediction made on the basis of previous knowledge on intermolecular double additions but was found to be correlated to the conformational strain of the tether moiety, which can be estimated by a newly developed ''double differential protocol''. Systematic studies on the reliability of various computational methods for organofullerenes indicated that certain molecular orbital and molecular mechanics calculations give very reliable structural data while certain others do not.
  • Fullerene that binds a metal on the pentagon
    E Nakamura, M Sawamura, W Iikura, S Mori
    PROCEEDINGS OF THE SYMPOSIUM ON RECENT ADVANCES IN THE CHEMISTRY AND PHYSICS OF FULLERENES AND RELATED MATERIALS, VOL 4 97 (14) 298 - 308 1997 [Refereed][Not invited]
  • M Sawamura, Y Kawaguchi, K Sato, E Nakamura
    CHEMISTRY LETTERS (8) 705 - 706 0366-7022 1997 [Refereed][Not invited]
     
    Under sonochemical conditions, various alkyl halides were converted into the corresponding alcohols in high yields through an aerobic radical reaction promoted by trialkyltin halide/NaBH3CN catalytic system.
  • M Sawamura, Y Nakayama, WM Tang, Y Ito
    JOURNAL OF ORGANIC CHEMISTRY 61 (26) 9090 - 9096 0022-3263 1996/12 [Refereed][Not invited]
     
    Enantioselective allylations of alpha-nitro ketones (3) and alpha-nitro esters (15) with allyl acetate were carried out in the presence of 2 equiv of alkali metal fluorides (KF, RbF, CsF) and 1 mol % of palladium catalysts prepared in situ from Pd-2(dba)(3) . CHCl3 and chiral phosphine ligands. Moderate enantioselectivities were observed in the reaction of nitro ketones 3, giving products 4 (4a, 49% ee; 4b, 58% ee; 4c, 44% ee) when rubidium fluoride and ferrocenylphosphine ligands bearing monoaza-15-crown-5 (Ib) or monoaza-18-crown-6 (Ic) moieties were used as a base and a chiral ligand, respectively. Optically active allylation product 4a was converted into 1-methyl-1-azaspiro[4.5]-decan-10-amine (13), a precursor to opioid receptor binding agents. Enantioselectivity in the reaction of nitro esters 15 increased in accord with increasing steric demand of the ester alkyl group (Me < Et < t-Bu). The highest selectivity (80% eel for the reaction of tert-butyl ester 15c was observed when the reaction was carried out at -40 degrees C in the presence of the palladium catalyst with the ligand (Ic) bearing a monoaza-18-crown-6 moiety, RbF (2 equiv), and RbClO4 (1 equiv). The pronounced effect of the crown ether moiety for both enantioselection and rate acceleration can be explained by assuming the formation of a ternary complex involving the crown ether, rubidium cation, and enolate anion at the stereodifferentiating transition state. Optically active nitro ester (R)-16c was converted into (R)-alpha-methylglutamic acid (20).
  • M Sawamura, H Iikura, E Nakamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 118 (50) 12850 - 12851 0002-7863 1996/12 [Refereed][Not invited]
  • Regio- and diastereocontrolled double cycloaddition to C-60 with new tris-annulating reagents
    H Isobe, H Tokuyama, M Sawamura, E Nakamura
    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 212 57 - ORGN 0065-7727 1996/08 [Refereed][Not invited]
  • E Nakamura, H Isobe, H Tokuyama, M Sawamura
    CHEMICAL COMMUNICATIONS (15) 1747 - 1748 1359-7345 1996/08 [Refereed][Not invited]
     
    Double cycloaddition of new tris-annulation reagents to [60]fullerene creates a tricyclic system constructed on the [60]fullerene sphere, providing Cs symmetric and C-2 chiral non-racemic organofullerenes.
  • M Sawamura, M Sudoh, Y Ito
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 118 (13) 3309 - 3310 0002-7863 1996/04 [Refereed][Not invited]
  • GOEKE A, SAWAMURA M, KUWANO R, ITO Y
    Angewandte Chemie, International Edition in English 35 (6) 662 - 663 1433-7851 1996/04/01 [Refereed][Not invited]
  • R KUWANO, M SAWAMURA, Y ITO
    TETRAHEDRON-ASYMMETRY 6 (10) 2521 - 2526 0957-4166 1995/10 [Refereed][Not invited]
     
    Asymmetric hydrogenation of dimethyl itaconate catalyzed by the transchelating chiral diphosphine (R,R)-(S,S)-EtTRAP-rhodium complex gave (S)-dimethyl 2-methylsuccinate with 96% ee. Dimethyl 2-isopropylidenesuccinate, a tetrasubstituted olefin substrate, was also hydrogenated with (R,R)-(S,S)-BuTRAP-rhodium complex in high enantioselectivity (78% ee), but with opposite enantioselection.
  • M SAWAMURA, H HAMASHIMA, M SUGAWARA, R KUWANO, Y ITO
    ORGANOMETALLICS 14 (10) 4549 - 4558 0276-7333 1995/10 [Refereed][Not invited]
     
    The trans-chelating chiral phosphine ligand (S,S)-(R,R)-2,2 ''-bis[1-(diphenylphosphino)- ethyl]-1,1 ''-biferrocene (la, abbreviated to PhTRAP) was synthesized from (S)-1-(N,N-dimethylamino)ethylferrocene (2) in four steps in 51% overall yield. (R,R)-(S,S)-PhTRAP and other arylTRAP derivatives (Ib, AnisTRAP; Ic, Cl-PhTRAP, Id, FurTRAP; le, Tol-PhTRAP) were synthesized in a similar manner. Through-space P-31-P-31 Spin couplings were observed indirectly in the H-1 and C-13{H-1} NMR spectra of la-e and directly in the P-31{H-1} NMR spectrum of asymmetrical TRAP le, indicating that the two phosphorus atoms of the ligands are in close proximity. Results of NOE experiments showed that PhTRAP is a fairly rigid molecule and in a conformation favorable for trans-chelation. As square planar transition metal complexes bearing arylTRAPs as trans-chelating ligands, trans-[PdX(2){(S,S)-(R,R)-PhTRAP}] (7, X = Pr; 8, X = I; 9, X = Cl), trans-[PtCl2{(R,R)-(S,S)-PhTRAP}] (10), trans-[PtCl2{(S,S)-(R,R)-1e}] (11), trans-[IrCl(CO){(S,S)-(R,R)-PhTRAP}] (12), trans-[RhCl(CO){(S,S)-(R,R)-PhTRAP}] (13), and trans-[RhCl(CO){(S,S)-(R,R)-FurTRAP}] (14) were prepared and fully characterized. X-ray crystal structures were determined for the palladium complex 7 and the rhodium complex 14.
  • M SAWAMURA, R KUWANO, Y ITO
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 117 (37) 9602 - 9603 0002-7863 1995/09 [Refereed][Not invited]
  • M SAWAMURA, H HAMASHIMA, H SHINOTO, Y ITO
    TETRAHEDRON LETTERS 36 (36) 6479 - 6482 0040-4039 1995/09 [Refereed][Not invited]
     
    Asymmetric Michael reaction of N-methoxy-N-methyl-2-cyanopropionamide with vinyl ketones or acrolein in the presence of 0.1-1 mol% of a rhodium catalyst prepared in situ from Rh(acac)(CO)(2) and a trans-chelating chiral diphosphine ligand (S,S)-(R,R)-PhTRAP gave optically active Michael adducts with high enantiomeric excesses (89-94%) in high yields. The adducts with methyl vinyl ketone was transformed into an alpha-cyano aldehyde and ketones with an quarternary asymmetric carbon center through the reaction with LiAlH4 or Grignard reagents.
  • SYNTHESIS AND CELLULAR CHARACTERIZATION OF THE DETRANSFORMATION AGENT, (-)-DEPUDECIN
    U SHIMADA, HJ KWON, M SAWAMURA, SL SCHREIBER
    CHEMISTRY & BIOLOGY 2 (8) 517 - 525 1074-5521 1995/08 [Refereed][Not invited]
     
    Background: (-)-Depudecin is a fungal metabolite that reverts the rounded phenotype of NIH3T3 fibroblasts transformed with v-ras and v-src oncogenes to the flat phenotype of the nontransformed parental cells. The mechanism of action of this detransformation agent is unknown. Although depudecin appears to be an excellent molecule; for probing signaling pathways that regulate changes in the cytoskeletal architecture, reagents based on depudecin are not available as it has not yet been successfully synthesized. We therefore set out to synthesize (-)-depudecin. Results: An asymmetric synthesis of(-)-depudecin has been developed. A cell staining assay has been used to reveal the ability of synthetic depudecin, but not several structural variants, to induce a flattened morphology in v-Ha-ras-transformed NIH3T3 cells. This assay also shows depudecin induces an intricate network of actin stress fibers in these cells and in MG63 osteosarcoma cells and reveals the essential role of the epoxide and hydroxyl moieties in depudecin. Cycloheximide and actinomycin D inhibited the ability of depudecin to induce a morphological change, suggesting that both mRNA synthesis and de novo protein synthesis are required for depudecin-mediated suppression of the transformed phenotypes in ras-transformed cells. Conclusions: The synthetic procedure provides access to (-)-depudecin and could be readily modified to produce depudecin-related reagents for the identification of depudecin's cellular target(s). This target appears to be involved in the regulation of the assembly of the actin microfilament component of the cytoskeleton in mammalian cells.
  • R KUWANO, M SAWAMURA, J SHIRAI, M TAKAHASHI, Y ITO
    TETRAHEDRON LETTERS 36 (29) 5239 - 5242 0040-4039 1995/07 [Refereed][Not invited]
     
    Asymmetric hydrosilylation of symmetrical diketones with diphenylsilane in the presence of catalytic amount ([substrate]/[catalyst] = 100) of rhodium complex coordinated with trans-chelating chiral phosphine ligand EtTRAP gave corresponding optically active symmetrical diols with high enantiomeric excesses.
  • M SAWAMURA, R KUWANO, J SHIRAI, Y ITO
    SYNLETT (4) 347 - 348 0936-5214 1995/04 [Refereed][Not invited]
     
    Asymmetric hydrosilylation of alpha-, beta-, and gamma-keto esters with diphenylsilane in the presence of 1 mol% of a rhodium catalyst containing trans-chelating chiral phosphine ligand EtTRAP gave optically active alcohols with enantiomeric excesses ranging between 32-93%.
  • M SAWAMURA, Y NAKAYAMA, T KATO, Y ITO
    JOURNAL OF ORGANIC CHEMISTRY 60 (6) 1727 - 1732 0022-3263 1995/03 [Refereed][Not invited]
     
    Asymmetric aldol reaction of N-methoxy-N-methyl-alpha-isocyanoacetamide (alpha-isocyano Weinreb amide) with aldehydes [RCHO: R = Ph, Me, i-Pr, (E)-MeCH=CH, (E)-BnOCH(2)CH=CH] in the presence of a gold(I) catalyst prepared in situ from [Au(c-HexNC)(2)]BF4 and chiral ferrocenylphosphine ligand (R)-N-methyl-N-(2-morpholinoethyl)-1-[(S)-1',2-bis(diphenylphosphino)ferrocenyl]ethylamine gave high yields of optically active trans-5-alkyl-2-oxazoline-4-(N-methoxy-N-methylcarboxamides) with high diastereo- and enantioselectivities. The diastereoselectivities (trans:cis) and enantiomeric excesses of the trans-oxazolines for the reaction with 1 mol % of the catalyst are as follows: R = Ph, 97:3, 96% ee; R = Me, 95:5, 97% ee; R = i-Pr, 98:2, 97% ee; R = (E)-MeCH=CH, 97:3; 99% ee; (E)-BnOCH(2)CH=CH, 96:4, 95% ee. These optically active oxazolines were converted to N,O-protected beta-hydroxy-alpha-amino aldehydes and ketone in high yields. An N-protected alpha-amino aldehyde (R = Ph) lacking the beta-hydroxyl group was also obtained through the catalytic hydrogenolysis of the oxazoline.
  • M SAWAMURA, H HAMASHIMA, Y ITO
    TETRAHEDRON 50 (15) 4439 - 4454 0040-4020 1994/04 [Not refereed][Not invited]
     
    Asymmetric Michael reaction of 2-cyanopropionates with vinyl ketones or acrolein in the presence of 0.1-1 mol% of a rhodium catalyst prepared in situ from RhH(CO)(PPh(3))(3) and a trans-chelating chiral diphosphine ligand (S,S)-(R,R)-PhTRAP in benzene at 3-5 degrees C gave optically active Michael adducts with high enantiomeric excesses (83-93% ee) in high yields. The reaction of 2-cyanopropionate with methacrolein and crotonaldehyde proceeded somewhat slowly, giving diastereomer mixtures in moderate enantioselectivities but in low diastereoselectivities. The reaction of 2-cyanobutyrate and 2-cyano-3-methylbutyrate with acrolein gave corresponding Michael adducts with much lower enantiomeric excesses than that of 2-cyanopropionates. The Michael addition product from acrolein was converted into an optically active alpha-methyl-alpha-amino acid.
  • SAWAMURA M, KUWANO R, ITO Y
    Angewandte Chemie, International Edition in English 33 (1) 111 - 113 1433-7851 1994 [Not refereed][Not invited]
  • M SAWAMURA, H SASAKI, T NAKATA, Y ITO
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 66 (9) 2725 - 2729 0009-2673 1993/09 [Not refereed][Not invited]
     
    The ferrocene analogue of salicylic acid, 2-hydroxyferrocenecarboxylic acid was synthesized via monolithiation of ferrocene with t-butyllithium, and resolved to optically active forms. Optically active 2-hydroxyferrocene-carboxylic acid was converted to 1-hydroxyferrocenecarbaldehyde, ferrocene analogue of salicylaldehyde, and 2-alkoxyferrocenecarboxylic acids. The later compounds were used as chiral carboxylato ligands for the rhodium(II)-catalyzed asymmetric intramolecular C-H insertion of alpha-diazo beta-keto esters (up to 42% ee).
  • M SAWAMURA, H HAMASHIMA, Y ITO
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 114 (21) 8295 - 8296 0002-7863 1992/10 [Not refereed][Not invited]
  • M SAWAMURA, Y ITO
    CHEMICAL REVIEWS 92 (5) 857 - 871 0009-2665 1992/07 [Not refereed][Not invited]
  • T HAYASHI, M SAWAMURA, Y ITO
    TETRAHEDRON 48 (11) 1999 - 2012 0040-4020 1992/03 [Not refereed][Not invited]
     
    Optically active ferrocenylbisphosphine ligands containing 2-(dialkylamino)ethylamino group on the ferrocenylmethyl position have been prepared and used for the gold(I)-catalyzed asymmetric aldol reaction of isocyanoacetate with aldehydes. Six-membered ring amines, such as morpholino or piperidino group, at the terminal of the side chain were most stereoselective to give optically active trans-4-methoxycarbonyl-5-alkyl-2-oxazolines (up to 97% ee) with high enantio- and diastereoselectivity in a quantitative yield.
  • SAWAMURA M, NAGATA H, SAKAMOTO H, ITO Y
    The Journal of the American Chemical Society 114 (7) 2586 - 2592 0002-7863 1992 [Not refereed][Not invited]
  • M SAWAMURA, A YAMAUCHI, T TAKEGAWA, Y ITO
    JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS (13) 874 - 875 0022-4936 1991/07 [Not refereed][Not invited]
     
    A new planar chiral bisphosphine, 2,2''-bis(diphenylphosphino)-1,1''-biferrocene (BIFEP), was synthesized via regioselective magnesiation of (diphenylphosphinyl)ferrocene, and converted to its palladium(II) complex.
  • M SAWAMURA, H HAMASHIMA, Y ITO
    TETRAHEDRON-ASYMMETRY 2 (7) 593 - 596 0957-4166 1991 [Not refereed][Not invited]
     
    A new chiral diphosphine ligand, (R,R)-(S,S)-2,2''-bis[1-(diphenylphosphino)ethyl]-1,1''-biferrocene, which possesses both central and planar elements of chirality, was synthesized. The NMR studies and molecular weight determination indicated that the ligand chelates to platinum(II) and palladium(II) in trans-manner.
  • Ttrahedron Letters 32 (24) 2799  1991 [Not refereed][Not invited]
  • SAWAMURA M, HAMASHIMA H, ITO Y
    The Journal of Organic Chemistry 55 (24) 5935 - 5936 0022-3263 1990 [Not refereed][Not invited]
  • M SAWAMURA, Y ITO, T HAYASHI
    TETRAHEDRON LETTERS 31 (19) 2723 - 2726 0040-4039 1990 [Not refereed][Not invited]
  • ITO Y, SAWAMURA M, HAMASHIMA H, EMURA T, HAYASHI T
    Tetrahedron Letters 30 (35) 4681 - 4684 0040-4039 1989 [Not refereed][Not invited]
  • M SAWAMURA, Y ITO, T HAYASHI
    TETRAHEDRON LETTERS 30 (17) 2247 - 2250 0040-4039 1989 [Not refereed][Not invited]

Industrial Property Rights

  • 新規なトリアルキルホスフィン誘導体
    特開2004-262782

Awards & Honors

  • 2019/02 The Society of Synthetic Organic Chemistry, Japan Synthetic Organic Chemistry Award
     Development of Carbon-Carbon Bond Forming Asymmetric Copper-Catalyzed Reactions 
    受賞者: SAWAMURA Masaya
  • 2018/03 根岸賞
     
    受賞者: 澤村 正也
  • 2017/01 名古屋シルバーメダル
     
    受賞者: 澤村 正也
  • 2015/02 有機合成化学協会 日産化学・有機合成新反応/手法賞
     
    受賞者: 澤村 正也
  • 2014/03 北海道大学研究総長賞
     
    受賞者: 澤村 正也
  • 2012/03 日本化学会学術賞
     
    受賞者: 澤村 正也
  • 1996/03 日本化学会進歩賞
  • 1989/02 有機合成化学協会 「研究企画賞」

Research Grants & Projects

  • 遷移金属錯体触媒の精密組織化と応用
    JST戦略的創造研究推進制度(個人研究型) (個人研究推進事業:さきがけ研究21‐PRESTO)
    Date (from‐to) : 2002 -2005
  • Atomic Level Organization of Transition Metal Complexes for Use in Organic Synthesis
    JST Basic Research Programs (Precursory Research for Embryonic Science and Technology :PRESTO)
    Date (from‐to) : 2002 -2005
  • 機能性有機金属化合物の開発
  • Development of Functional Organometallic Compounds

Educational Activities

Teaching Experience

  • Molecular Chemistry A (Organometallic Chemistry)
    開講年度 : 2018
    課程区分 : 修士課程
    開講学部 : 総合化学院
    キーワード : 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
  • Organic Chemistry Ⅰ
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 理学部
    キーワード : 反応、合成、付加反応、置換反応、脱離反応、酸性度
  • Chemistry II
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 有機化合物、官能基、分子構造、化学的性質、化学反応、機能性有機物、生体関連有機物質

Campus Position History

  • 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 
    環境保全センター長
  • 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

Position History

  • 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 
    環境保全センター長
  • 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


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