PREPARATION OF OPTICALLY ACTIVE CIS-1,3-DIBENZYL-HEXAHYDRO-1H-FURO(3,4-D)IMIDAZOLE-2,4-DIONE AND ITS INTERMEDIATES

摘要

A process for preparing an optically active cis-1,3-dibenzylhexahydro-1H-furo[3,4-d]imidazole-2,4-dione of the formula: (I) wherein an asterisk (*) indicates an asymmetric carbon, Bzl represents a benzyl group and the 3a- and 6a-positions take the cis-configuration, which comprises reducing selectively an optically active cis-imidazolidinedicarboxylic acid monoester of the formula: (III) wherein R is a C1-C6 alkyl group and Bzl is as defined above with a reducing agent at either one of the carboxyl group and the alkoxycarbonyl group in the said monoester, followed by cyclization, the said monoester being the one obtainable by hydrolysis of a cis-imidazolidinedicarboxylic acid diester of the formula: (II) wherein R and Bzl are each as defined above with an enzymatic material having a capability of hydrolyzing the ester group in the said diester.