''AN IMPROVED PROCESS FOR THE ENZYMATIC PREPARATION OF (-)-CIS- LAMIVUDINE

摘要

The present invention relates to an improved process for the preparation of cis (-) lamivudine. The process of this invention comprises the step of enantio- and stereoselective hydrolysis of a racemic mixture of 1,3-oxathiolane nucleoiside analogues of formula 2 wherein RCO is a substituted carbonyl derivative where the non-carbonyl moiety R of the ester is selected from straight or branch chained alkyl (e.g. methyl, ethyl, n-propyl, n-butyl), alkoxyalkyl (e.g. phenyl optionally substituted by hydroxy, or halogen), and aminoacid esters (e.g. L-valyl, or L-isoleucyl) with enzyme pencillin G acylase at a temperature in the range of 15-40 deg. C for a period of 2-24 hrs, recovering the product by known methods.