Chemical and Biochemical Studies on a New Alcohol Dehydrogenase

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Asymmetric reduction of caronyl compounds utilizing a yeast, Yamadazyma farinosa IFO 10896, has been developed. It was revealed that this yeast has the ability to reduce not only methyl ketones but also trifluoromethyl ketones in a highly enantioselective manner. The spacial arrangement of the ligands around the asymmetric carbon of the resulting alcohols are the same with each other. The sulfur functionalities on the other side of the carbonyl group are effective topromote the reaction and its stereochemical selectivity. It is worth noting that the configuration of the sulfoxide moiety on the α position of the carbonyl have serious effect on the enantioselectivity of the reaction, in which (S)-sulfoxide gave the higher selectivity.Methyl ketones with an acetal functionality are also good substrates to this biocatalyst. The optically active hydroxy aldehyde can be derived to optically active diols by the following derivations utilizing organometallic reagents.α-Hydroxy ketones were also subjected to the mycrobial reductions. For example, α- hydroxyacetophenone was smoothly reduced to (S)-styrene glycol. As the hydrooxymethyl group and phenyl ring can be separately oxidized to aldehyde functionality, the carbon-chain elongation is possible to both sides of the resulting chiral center. Mono-protected dihydroxyacetones were also reduced by this yeast. However, the selectivity and reactivity are desirable to be more improved.