Design of <i>N</i>-Spiro <i>C</i><sub>2</sub>-Symmetric Chiral Quaternary Ammonium Bromides as Novel Chiral Phase-Transfer Catalysts: Synthesis and Application to Practical Asymmetric Synthesis of α-Amino Acids
作者:Takashi Ooi、Minoru Kameda、Keiji Maruoka
DOI:10.1021/ja021244h
日期:2003.4.1
C(2)-symmetric chiralquaternaryammonium bromides 10 and 11 have been designed as a new, purely synthetic chiral phase-transfer catalyst, and readily prepared from commercially available optically pure 1,1'-bi-2-naphthol as a basic chiral unit. The details of the synthetic procedures of each requisite chiral binaphthyl subunit have been disclosed, and the structures of the assembled N-spiro chiral quaternary
Reversal of Enantioselectivity by Tuning the Conformational Flexibility of Phase-Transfer Catalysts
作者:Ming-Qing Hua、Han-Feng Cui、Lian Wang、Jing Nie、Jun-An Ma
DOI:10.1002/anie.200906814
日期:2010.4.1
Towards perfect asymmetric catalysis: When binol‐derived N‐spiro quaternary ammonium salts were used as phase‐transfer catalysts in the conjugate addition of nitroalkanes to chalcones and its analogues, an intriguing reversal of enantioselectivity was observed. Novel chiral catalysts have been designed and synthesized (see structure).
New, Chiral Phase Transfer Catalysts for Effecting Asymmetric Conjugate Additions of α-Alkyl-α-cyanoacetates to Acetylenic Esters
作者:Xisheng Wang、Masanori Kitamura、Keiji Maruoka
DOI:10.1021/ja068119g
日期:2007.2.1
A new, chiral phasetransfercatalyst has been designed for the development of a general and useful procedure on the hitherto unknown, asymmetric conjugate additions of α-substituted-α-cyanoacetates to acetylenic esters with high enantioselectivity and moderate E/Z selectivity.
Optically active quarternary ammonium salt with axial chirality, method for producing thereof, and application thereof for asymmetric synthesis of &agr;-amino acid
申请人:Nagase & Co., Ltd.
公开号:US06340753B1
公开(公告)日:2002-01-22
A novel optically active quarternary ammonium salt with an axial chirality is provided. The quarternary ammonium salt can act as a phase-transfer catalyst to convert glycine derivatives into optically active &agr;-amino acid derivatives by stereoselectively alkylating the glycine derivatives. Furthermore, according to the present invention, intermediates useful for producing the novel quarternary ammonium can be produced.