Asymmetric reductions in aqueous media: enzymatic synthesis in cyclodextrin containing buffers

The enzymatic reduction of hydrophobic ketones in cyclodextrin containing m edia is reported yielding the corresponding alcohols (S)-1-(2-naphthyl)-eth anol, (S)-(E)-4-phenyl-3-en-2-ol and 1,2,3,4-tetrahydro-2-(1-hydroxyethyl)- 1-oxonaphthalene in good yield and high enantiomeric excess. The reaction w as catalyzed by a carbonyl reductase from Candida parapsilosis, NADH regene ration was carried out using either 2-propanol in a substrate coupled mode or formate dehydrogenase from Candida boidinii and formate as hydrogen dono r. In continuous experiments high stability of the enzymes in media contain ing heptakis-(2,6-di-O-methyl)-beta-cyclodextrin could be demonstrated. Spa ce time yields of 120 g/(Ld) were obtained under not yet optimized conditio ns during the production of (S)-1-(2-naphthyl)-ethanol. (C) 1999 Elsevier S cience Ltd. All rights reserved.