Enzymatic resolution of (±)-conduritol-B, a key intermediate for the synthesis of glycosidase inhibitors

Lipases from porcine pancreas, Candida cylindracea and Mucor miehei (adsorbed on support, Lipozyme® IM) catalysed in t-butylmethylether the alcoholysis of rac-conduritol-B peracetate, (±)-1, by n-butanol to give enantiopure (2S,3S)-diacetoxy-(1R,4R)-dihydroxycyclohex-5-ene, (-)-3, and (1S,2R,3R,4S)-tetraacetoxy-cyclohex-5-ene, (+)-1. The enantioforms (+)- and (-)-conduritol-B, obtained after chemical hydrolysis of (-)-3 and (+)-1, respectively, may be employed to prepare both the enantiomers of conduritol-B epoxide and cyclophellitol, powerful inhibitors of glycosidases.