Preparation of the enantiomers of 1-phenylethan-1,2-diol.: Regio- and enantioselectivity of acylase I and Candida antarctica lipases A and B

Acylase 1 and Cundida antarctica lipases A (CAL-A) and B (CAL-B) were evaluated for the preparation of the enantiomers of 1-phenylethan-1,2-diol. In the presence of CAL-B, the sequential one-pot methanolysis of the diacetate in acetonitrile allowed the preparation of (S)-diol (e.e. 97%) and (R)-1-acetoxy-1-phenylethanol (e.e. 94%). Base-catalyzed methanolysis of the monoacetate resulted in the corresponding (R)-diol. When one of the diol enantiomers wets subjected to Mitsunobu esterification, inversion of configuration occurred, allowing transformation of the initially racemic mixture to one enantiomer. Acylase 1-catalysis led to the chemo- and enantioselective formation of (S)-1-acetoxy-1-phenylethanol (e.e. 97%) in the presence of the primary hydroxyl function through acetylation of the secondary hydroxyl group. The low chemical yield (ca. 25%) was due to the moderate enzymatic regioselectivity. CAL-A behaved in a similar way to acylase 1. (C) 2001 Elsevier Science Ltd. All rights reserved.