Stereochemical Control in Microbial Reduction. Part 10. Asymmetric Reduction of Alkyl 3-Methyl-2-Oxobutanoate with Immobilized Bakers' Yeast in Hexane |
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| Authors: | Kaoru Nakamura Takehiko Miyai Kiyoko Inoue Seiji Kawasaki Shinzaburo Oka Atsuyoshi Ohno |
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| Institution: |
a Department of Chemistry, Shiga University of Medical Science, Seta, Ohtsu, Japan
b Institute for Chemical Research, Kyoto University, Uji, Kyoto, Japan |
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| Abstract: | Esters of 3-methyl-2-oxobutanoic acid are reduced with bakers' yeast by three methods: free bakers' yeast in water, immobilized bakers' yeast in water, and immobilized bakers' yeast in hexane. Although (R)-hydroxy esters are obtained in all cases, the enantiomeric excess varies from 3% (reduction of the methyl ester with free bakers' yeast in water) to 93% (reduction of the butyl ester with immobilized bakers' yeast in hexane) depending on the structure of substrate and on the reaction conditions. The mechanism of the present stereochemical control is discussed. |
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| Keywords: | Reduction immobilization bakers' yeast hexane α-keto esters α-hydroxy esters |
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