2-chloro-alkanoic acids 6 and 7 have been obtained the diastereoselective halogenation of chiralsilylketeneacetals 3a-f, and subsequent saponification of the resulting crude esters. Examples characterized by e.e. values up to 95% are reported. The diastereoface selectivity is independent of the silylketeneacetal configuration.
The absolute stereochemistry of chiral carboxylicacids is determined as a di(1‐naphthyl)methanol ester derivative. Computational scoring of conformations favoring either P or M helicity of the naphthyl groups, capable of exciton‐coupled circular dichroic coupling, leads to a predicted stereochemistry for the derivatized carboxylicacids.
NOVEL METOD FOR THE SYNTHESIS OF PERINDOPRIL AND THE PHARMACEUTICALLY-ACCEPTABLE SALTS THEREOF
申请人:Dubuffet Thierry
公开号:US20070043103A1
公开(公告)日:2007-02-22
A process for the synthesis of perindopril of formula (I):
and its pharmaceutically acceptable salts.
一种合成公式(I)的贝那普利及其药用盐的过程。
Enzymatic Hydrolysis and Selective Racemisation Reactions of α-Chloro Esters
作者:Louise Haughton、Jonathan M. J. Williams
DOI:10.1055/s-2001-13395
日期:——
The kinetic resolution of a-chloro esters was effected with good selectivity using CLEC (Cross-Linked Enzyme Crystals) enzymes. The selective racemisation of a-chloro esters in the presence of alpha -chloro acids enabled a successful dynamic kinetic resolution reaction to be performed.
Asymmetric transformation of racemic 2-phenyl- and 2-chloroalkanoic acids via oxazolines into the corresponding optically active acids was investigated using (S)-phenylalaninol as a chiral auxiliary. The asymmetric transformation was performed by metalation of the oxazolines with butyllithium followed by protonation of the resulting lithiooxazolines. 2-Phenyl- and 2-chloroalkanoic acids were obtained in the optical yields of 29–53% and 45–73%, respectively, by the acidic hydrolysis of the chiral oxazolines thus formed. The mechanism of the asymmetric transformation was discussed.