Enzymes in organic synthesis. 28. Reinvestigation of the horse liver alcohol dehydrogenase-catalyzed reductions of 2-alkylcyclohexanones.Identification of cis -alkylcyclohexanols as minor products

Abstract

The formation of cis-2-alkylcyclohexanol products from horse liver alcohol dehydrogenase-catalyzed reductions of 2-alkylcyclohexanones has been detected for the first time. The cis-alcohols are minor (<4%) products, with the isomeric trans-products being heavily predominant under all conditions. cis-Alcohol production can be suppressed by suitable manipulation of the reaction conditions. Exclusive formation of the trans-alcohols is favoured by operating in an appropriate buffer such as Tris-HCl at the lowest [E]/[S] and pH conditions possible, and by minimizing the reaction time. The results parallel the cis-alcohol formation observed previously with the analogous 3-alkyltetrahydrothiopyran-4-one substrates.