Patent ID: 8158406

Claim:
A process for the enantioselective enzymatic reduction of keto compounds of formula I R 1 —C(O)—R 2 (I) in which R1 stands for one of the moieties 1) —(C 1 -C 20 )-alkyl, wherein alkyl is linear-chain or branched, 2) —(C 2 -C 20 )-alkenyl, wherein alkenyl is linear-chain or branched and optionally contains up to four double bonds, 3) —(C 2 -C 20 )-alkynyl, wherein alkynyl is linear-chain or branched and optionally contains up to four triple bonds, 4) —(C 6 -C 14 )-aryl, 5) —(C 1 -C 8 )-alkyl-(C 6 -C 14 )-aryl, 6) —(C 5 -C 14 )-heterocycle which is unsubstituted or substituted one, two or three times by —OH, halogen, —NO 2 and/or —NH 2 , or 7) —(C 3 -C 7 )-cycloalkyl, wherein the moieties mentioned above under 1) to 7) are unsubstituted or substituted one, two or three times, independently of each other, by —OH, halogen, —NO 2 and/or —NH 2 , and R 2 stands for one of the moieties 8) —(C 1 -C 6 )-alkyl, wherein alkyl is linear-chain or branched, 9) —(C 2 -C 6 )-alkenyl, wherein alkenyl is linear-chain or branched and optionally contains up to three double bonds, 10) —(C 2 -C 6 )-alkynyl, wherein alkynyl is linear-chain or branched and optionally contains two triple bonds, or 11) —(C 1 -C 10 )-alkyl-C(O)—O—(C 1 -C 6 )-alkyl, wherein alkyl is linear or branched and is unsubstituted or substituted one, two or three times by —OH, halogen, —NO 2 and/or —NH 2 , wherein the moieties mentioned above under 8) to 11) are unsubstituted or substituted one, two or three times, independently of each other, by —OH, halogen, —NO 2 and/or —NH 2 , comprising treating a liquid, single-phase mixture comprising (a) at least 5% by weight/by volume of a compound of formula (I), (b) at least 15% by volume of 2-propanol and/or 2-butanol, and (c) water with an R-specific oxidoreductase in the presence of a cofactor to form achiral hydroxy compound of general formula II R 1 —CH(OH)—R 2 (II) wherein R 1 and R 2 have the above-indicated meaning, and whereby the R-specific oxidoreductase continuously regenerates the cofactor by oxidation of the 2-propanol and/or the 2-butanol.