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Facile and Efficient Enantioselective Strecker Reaction of Ketimines by Chiral Sodium Phosphate
Author(s) -
Shen Ke,
Liu Xiaohua,
Cai Yunfei,
Lin Lili,
Feng Xiaoming
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200900210
Subject(s) - strecker amino acid synthesis , enantioselective synthesis , chemistry , trimethylsilyl cyanide , cyanohydrin , steric effects , organic chemistry , yield (engineering) , enantiomer , alkali metal , catalysis , nucleophile , medicinal chemistry , materials science , metallurgy
Asymmetric catalysis : A facile enantioselective Strecker reaction of ketimines with trimethylsilyl cyanide (TMSCN) was realized by employing chiral ( S )‐BNPNa 3 e and PBAP as an additive (see image). A wide substrate scope and good‐to‐excellent enantioselectivities were achieved.A facile and efficient enantioselective Strecker reaction of ketimines catalyzed by a chiral alkali‐metal salt has been developed. When 10 mol % BNPNa (BNP=1,1′‐binaphthyl‐2,2′‐diylphosphate) prepared in situ and 10 mol % para ‐ tert ‐butyl‐ ortho ‐adamantylphenol (PBAP) were introduced into the reaction, up to 96 % yield and up to 95 % ee ( ee =enantiomeric excess) were obtained. Both aliphatic and aromatic ketimines, especially sterically bulky cyclic ketimines derived from β‐acetonaphthone, α‐indanone, and α‐tetralone were found suitable for this reaction. On the basis of the experimental results and previous reports, trimethylsilyl cyanide (TMSCN) was indicated to be the real reactive nucleophile despite the existence of PBAP, and a possible working model was proposed to explain the origin of the asymmetric induction. The facile availability of 1,1′‐binaphthyl‐2,2′‐diylphosphoric acid (BNPH) and the simplicity of the procedure are beneficial for practical applications.