Enzyme-catalysed kinetic resolution of 4-endo-hydroxy-2-oxabicyclo[3.3.0]oct-7-en-3-one and employment of the pure enantiomers for the synthesis of anti-viral and hypocholestemic agents.

The endo-hydroxylactone (+/-)-(1) was resolved by enantioselective acetylation using Candida cylindracea lipase or preferentially Pseudomonas fluorescens lipase (pfl). Alternatively the corresponding butyrate (+/-)-(3) was hydrolysed with pfl to give the ester (+)-(1S,4R,5S)-(3) and the alcohol (-)-(1R,4S,5R)-(1). The latter compound was converted into carbovir (-)-(1R,4S)-(12) while the ester (+)-(3) was transformed into the delta-lactone (+)-(3R,5S)-(18). The exo-hydroxylactone (+/-)-(2) was resolved less efficiently by a trans-esterification process employing pfl and vinyl acetate.