Rhizopus oryzae, deracemization

Figure 18.21. Deracemization of benzoin (62) by Rhizopus oryzae ATCC 9363.

It is well known that various microbial systems are able to deracemise racemic secondary alcohols via a process that generally involves two different alcohol dehydrogenases with complementary enantiospecificity. For example racemic benzoin may be deracemized using Rhizopus oryzae ATCC 9363 (Scheme 4.38). Interestingly, through control of the pH of the medium, it was possible to control the absolute configuration of the major enantiomer produced at pH 7.5-8.S, the (J )-enantiomer was produced in 75% yield and 97% ee whereas at pH 4-5, the (S)-enantiomer was produced in 71% yield and 85% ee [89]. 

Comasseto ]V, Assis LF, Andrade LH, Schoenlein-Crusius IH, Porto ALM. Deracemization of aryl ethanols and reduction of acetophenones by whole fungal cells of Aspergillus ter-reus CCT 4083, A. terreus CCT 3320 and Rhizopus oryzae CCT 4964. /. Mol. Catal. B Enzym. 2006 39 24- 0. 

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