Enantiomerically enriched bifunctional sec-alcohols prepared by Candida antarctica lipase B catalysis. Evidence of non-steric interactions

Transesterification catalysed by Candida antarctica lipase B was used for the preparation of enantiomerically enriched bifunctional sec-alcohols. The enantiomeric ratio, E, for 3-butyn-2-ol was increased from 1.3 to over 500 by adding an easily removable protecting group. Kinetic resolution of bromohydrins and chlorohydrins bearing a halogen on the large substituent showed high enantioselectivity (E>80). On the other hand, halohydrins with the halogen on the medium group showed low E. Large differences in enantioselectivity were found by substituting the halogen atom of 1-halo-2-alkanols by a methyl group. These differences corresponded to more than 2 kcal mol(-1) and were ascribed to non-steric interactions. (C) 1997 Elsevier Science Ltd. All rights reserved.