Patent ID: 6909011

Claim:
A process for preparing protected, enantiomer-enriched cyanohydrins of the formula where R1 and R2 independently of one another can be an unsubstituted, monosubstituted or polysubstituted C 1 -C 20 -alkyl, C 5 -C 20 -aryl, C 5 -C 20 -heteroaryl, C 5 -C 20 -alkaryl, C 5 -C 20 -alkylheteroaryl or C 5 -C 20 -aralkyl radical or an unsubstituted, monosubstituted or polysubstituted C 5 -C 20 -heterocycle, or C 5 -C 20 -alkylheterocycle or together can be an unsubstituted or substituted C 4 -C 20 -alkylene radical, which can contain one or more heteroatoms in the chain, or one of the radicals is hydrogen, and R3 can be an unsubstituted or substituted C 1 -C 20 -alkyl, C 5 -C 20 -aryl or C 5 -C 20 -heteroaryl radical, which process comprises reacting an aldehyde or ketone of the formula where R1 and R2 are defined as above, in the presence of an (R)- or (S)-hydroxynitrile lyase in an organic, aqueous or 2-phase system of substantially water-immiscible diluent and water or in emulsion at a temperature of −5 to +40° C. with a carbonic ester nitrile of the formula where R3 is defined as above, to give the corresponding O-protected, enantiomer-enriched cyanohydrins of the formula (I).