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2001 Fiscal Year Final Research Report Summary

Catalytic Asymetric Reactions with Novel Chiral Catalysts Bearing a Flexible Chiral Reaction Field around the Metal Atom

Research Project

Project/Area Number 10208207
Research Category

Grant-in-Aid for Scientific Research on Priority Areas (B)

Allocation TypeSingle-year Grants
Research InstitutionKyoto University

Principal Investigator

KUWANO Ryoichi  Kyoto University, Graduate School of Engineering, Assistant Professer, 工学研究科, 助手 (20273477)

Project Period (FY) 1998 – 2000
KeywordsCatalytic Asymmetric Synthesis / Chiral Phosphine / Asymmetric Hydrogenation / Optically Active Pyrazine / Heteroaromatics / Indole
Research Abstract

Less flexibility of chiral catalyst is expected to provide more effective stereocontrol in catalytic asymmetric reactions. In this study, we prepared new optically active bisphosphines (TRAP) bearing flexible primary alkyl groups on the phosphorus atoms, and applied the chiral bisphosphines into enantioselective hydrogenation of unsaturated heterocycles.
The chiral bisphosphines TRAP were synthesized from optically active N,N-dimethyl-1-ferrocenylethylamine in 4 steps. TRAP ligands generally coordinate to a metal atom in trans-chelate fashion, but the reaction with PtCl_2(MeCN)_2 gave the mixture of trans- and cis-chelating platinum complex. i-Pr- and i-BuTRAP chelated to platinum atom in only trans-manner. By contrast, MeTRAP formed only cis-chelating complex.
TRAP ligands were effective in the asymmetric hydrogenation of 1,4,5,6-tetrahydropyrazine-2-carboxamide (eq.1). (R,R)-(S,S)-i-BuTRAP exhibited the highest enantioselectivity, 97% ee (S). Interestingly, (R,R)-(S,S)-MeTRAP showed a chiral sense of enantioselection opposite to other (R,R)-(S,S)-TRAP ligands, giving the hydrogenation product with 85% ee (R).
Asymmetric hydrogenation of heteroaromatic compounds has been unexplored in spite of its usefulness. Herein, we examined the asymmetric hydrogenatipn of indoles. The rhodium complexes prepared from Rh(acac)(cod) and various commercially available chiral bisphosphines were possible to catalyze the hydrogenation of 2-substituted indole, but resulting in non-enantioselective hydrogenation (0-1% ee). However, PhTRAP showed high enantioselectivity (85% ee) for the hydrogenation. [Rh(nbd)_2]SbF_6-PhTRAP-Cs_2CO_3 catalyst was found to be the most effective catalyst, giving optically active 2-substituted indolines with 94% ee (eq.2).

  • Research Products

    (10 results)

All Other

All Publications (10 results)

  • [Publications] Ryoichi Kuwano: "Synthesis of Trans-Chelating Chiral Diphosphine Ligand with Only Planar Chirality and Their Application to Asymmetric Hydrosilylation of Ketones"Tetrahedron Letters. 40. 1327-1330 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ryoichi Kuwano: "Asymmetric Hydrogenation of 1,4;5,6-Tetrahydropyrazine-2-(N-tert-butyl)carboxamide Catalyzed by Trans-Chelating Chiral Diphosphine-Rhodium Complexes"The Journal of Organic Chemistry. 64. 1232-1237 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ryoichi Kuwano: "Catalytic Asymmetric Allylation of Prochiral Nucleophiles,α-Acetamido-β-ketoesters"Journal of the American Chemical Society. 121. 3236-3237 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ryoichi Kuwano: "Enantioselective Construction of Quaternary α-Carbon Centers on α-Amino Phosphonates via Catalytic Asymmetric Allylation"Organic Letters. 1. 837-839 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ryoichi Kuwano: "Catalytic Asymmetric Hydrogenation of 1-Aza-2-cycloalkene-2-carboxylates Catalyzed by a Trans-Chelating Chiral Diphosphine PhTRAP-Rhodium Complex"Tetrahedron Letters. 40. 9045-9049 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ryoichi Kuwano: "Asymmetric Hydrosilylation of Ketones Using Trans-Chelating Chiral Bisphosphine Ligands Bearing Primary Alkyl Substituents on Phosphorus Atoms"Bulletin of the Chemical Society of Japan. 73. 485-496 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ryoichi Kuwano: "Hydrogenation of Five-Membered Heteroaromatic Compounds Catalyzed by a Rhodium-Phosphine Complex"Chemistry Letters. 428-429 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ryoichi Kuwano: "Asymmetric Aldol Reaction of 2-Cyanopropionates Catalyzed by a Trans-Chelating Chiral Diphosphine-Rhodium(I)Complex: Highly Enantioselective Construction of Quatemary Chiral Carbon Centers at α-Positions of Nitriles"Journal of Organometallic Chemistry. 603. 18-29 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ryoichi Kuwano: "Catalytic Asymmetric Hydrogenation of Heteroaromatic Compounds,Indoles"Journal of the American Chemical Society. 121. 7614-7615 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ryoichi Kuwano: "Catalytic Asymmetric Hydrogenation of α-(Acetamido)acrylates Using TRAP Trans-Chelating Chiral Bisphosphine Ligands:Remarkable Effects of Ligand P-Substituent and Hydrogen Pressure on Enantioselectivity"Bulletin of the Chemical Society of Japan. 73. 2571-2578 (2000)

    • Description
      「研究成果報告書概要(和文)」より

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Published: 2003-09-17  

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