Shifting the equilibrium of a biocatalytic cascade synthesis to enantiopure epoxides using anion exchangers

Hydroxide-loaded anion exchangers have been successfully employed to shift the equilibrium of a one-pot, two-step, two-enzyme cascade reaction affording enantiopure epoxides starting from prochiral alpha-chloroketones. The alpha-chloroketones were asymmetrically reduced employing an alcohol dehydrogenase and then transformed further to the corresponding epoxides employing halohydrin dehalogenases. Each epoxide enantiomer could be obtained with LIP to 93% conversion in enantiomerically Pure form (> 99% ee). In contrast to previous studies the amount of hydride donor (2-propanol) Could be reduced due to favoured halohydrin formation in the reduction of alpha-chloroketones. (c) 2009 Elsevier Ltd. All rights reserved.