Journal of Industrial Microbiology & Biotechnology 2008-11-01

Effect of ionic liquid [BMIM][PF6] on asymmetric reduction of ethyl 2-oxo-4-phenylbutyrate by Saccharomyces cerevisiae.

Yu-Gang Shi, Yun Fang, Yue-Ping Ren, Hong-Ping Wu, Hui-Lei Guan

Index: J. Ind. Microbiol. Biotechnol. 35(11) , 1419-24, (2008)

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Abstract

The effect of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) on the asymmetric reduction of ethyl 2-oxo-4-phenylbutyrate (EOPB) to synthesize optical active ethyl 2-hydroxy-4-phenylbutyrate (EHPB) catalyzed by Saccharomyces cerevisiae was investigated. (R)-EHPB [70.4%, e.e.(R)] is obtained using ethyl ether or benzene as the solvent. The main product is (S)-EHPB [27.7%, e.e.(S)] in [BMIM][PF6]. However, in ionic liquid-water (10:1, v/v) biphasic system, the enantioselectivity of the reduction is shifted towards (R)-side, and e.e.(R) is increased from 6.6 to 82.5% with the addition of ethanol (1%, v/v). The effect of the use of [BMIM][PF6] as an additive in relatively small amounts on the reduction was also studied. We find that there is a decline in the enantioselectivity of the reduction in benzene. In addition, a decrease in the conversion of EOPB and the yield of EHPB with increasing [BMIM][PF6] concentrations occurs in either organic solvent-water biphasic systems or benzene.