Catalyzed enantiomeric selection of 1,2-diols and their cyclization to produce oxiranes

A method of preparing an optically active ester of the formula ##STR18## wherein R and R.sup.1 are independently cycloalkyl, aryl, aralkyl, a heterocyclic group or a C.sub.1 -C.sub.4 alkyl-heterocycle, each being optionally substituted, provided that R and R.sup.1 are not identical, R.sup.2 is alkyl, aryl or aralkyl each optionally substituted, and * is an optically active chiral centre, said method comprising asymmetrically hydrolysing a racemic ester compound of formula (II) ##STR19## with a hydrolase selected from the group consisting of pig pancreatic lipase or lipase from Chromobacterium viscosum, wherein R, R.sup.1 and R.sup.2 are as defined above, thereby forming a reaction mixture optically active with respect to said ester, and optionally isolating said optically active ester from said reaction mixture.

A method of preparing an optically active diol of the formula ##STR20## wherein R and R.sup.1 are independently cycloalkyl, aryl, aralkyl, a heterocyclic group or a C.sub.1 -C.sub.4 alkyl-heterocycle, each being optionally substituted, provided that R and R.sup.1 are not identical, and * is an optically active chiral centre, said method comprising asymmetrically transesterifying a racemic compound of formula (III) ##STR21## with an acyl donor and a hydrolase selected from the group consisting of pig pancreatic lipase or lipase from Chromobacterium viscosum, wherein R and R.sup.1 are as defined above, thereby forming a reaction mixture optically active with respect to said diol, and optionally isolating said optically active diol from said reaction mixture.