DOUBLE ENANTIOSELECTIVE TRANSESTERIFICATION OF RACEMIC CARBOXYLIC ESTERS AND CYCLIC MESO-DIOLS BY LIPASE CATALYSIS

Lipase-catalysed double enantioselective transesterifications of racem ic carboxylic esters and cyclic meso-diols to give the hydroxy- esters 3, 6, 9, 11 and 14 have been investigated. The selectivity of this pr ocess is determined by the structure of both substrates and the origin of the lipase. In four of the five cases investigated, lipase SP 382 shows the highest activity and selectivity. In the products, excepting the acyl part of compounds 3, (S)-selectivity for both the alcohol an d the acyl moiety has been observed. However, regarding the acyl part the selectivity is poor compared with that of the alcohol part. Applic ation of this method allows us to prepare enantiomerically pure compou nds with at least three asymmetric centres in one biocatalytic step if the reaction partners are matching and/or the products are easy to se parate as found for compounds 9a, 9e and 11 a for instance. The X-ray molecular structures of compounds 9a and 11a are reported.