Chemical and Biochemical Studies on a New Alcohol Dehydrogenase

利用酵母Yamadazyma farinosa IFO 10896不对称还原caronyl化合物。结果表明，该酵母不仅具有还原甲基酮的能力，而且具有高度对映选择性还原三氟甲基酮的能力。配体在醇的不对称碳原子周围的空间排列是相同的。羰基另一侧的含硫官能团对反应的进行和立体化学选择性有很大的促进作用。值得注意的是，羰基α位上亚砜的构型对反应的对映选择性有很大的影响，其中（S）-亚砜的选择性较高，具有缩醛官能团的甲基酮也是该生物催化剂的良好底物。光学活性的羟基醛可以用有机金属试剂通过下列衍生化反应得到光学活性的二醇。α-羟基酮也可以用微生物还原。例如，α-羟基苯乙酮被顺利地还原为（S）-苯乙烯乙二醇。由于羟基甲基和苯环可以分别氧化为醛官能团，因此碳链可以向所得手性中心的两侧延伸。单保护的二羟基丙酮也减少了这种酵母。然而，希望进一步改进选择性和反应性。

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.