Patent ID: 8361765

Claim:
A method for the enantioselective reduction of a keto compound of the formula I R 1 —C(O)—R 2 (I) where R 1 and R 2 are, independently of one another, identical or different and are (i) a hydrogen atom; (ii) —(C 1 -C 20 )-alkyl in which alkyl is straight-chained or branched; (iii) —(C 2 -C 20 )-alkenyl in which alkenyl is straight-chained or branched and, optionally, comprises one, two, three or four double bonds; (iv) —(C 2 -C 20 )-alkynyl in which alkynyl is straight-chained or branched and, optionally, comprises one, two, three or four triple bonds; (v) —(C 6 -C 14 )-aryl; (vi) —(C 1 -C 8 )-alkyl-(C 6 -C 14 )-aryl or (vii) R 1 and R 2 form in combination with the —C(O) radical a —(C 6 -C 14 )-aryl or a —(C 5 -C 14 )-heterocycle, where the radicals defined above under (i) to (vii) are unsubstituted or, independently of one another, mono- to trisubstituted by —OH; halogen; —NO 2 ; —C(O)—O—(C 1 -C 20 )-alkyl in which alkyl is linear or branched and unsubstituted or mono- to trisubstituted by halogen, hydroxyl, amino or nitro, or —(C 5 -C 14 )-heterocycle which is unsubstituted or mono- to trisubstituted by halogen, hydroxyl, amino or nitro, said method comprising (a) admixing a reaction batch comprising a compound of the formula (I) in a proportion of from 10% to 25%, based on the total volume of the reaction batch, with alcohol dehydrogenase, water, cofactor NADPH or NADH and an organic solvent having a logP of from 0.6 to 3.0; (b) incubating a two-phase system of water, organic solvent and the compound of formula (I) to produce a chiral hydroxyl compound and oxidized cofactor; (c) continuously regenerating cofactor from oxidized cofactor produced by said alcohol dehydrogenase, and (d) isolating the chiral hydroxy compound.