Biocatalytic oxidation of sec-alcohols via hydrogen transfer

The oxidations of alcohols via hydrogen transfer represents an environmental benign ‘green’ redox protocol. In this context biocatalytic hydrogen transfer employing the alcohol dehydrogenase ADH-‘A’ from Rhodococcus ruber DSM 44541 results in oxidation of sec-alcohols in aqueous medium at room temperature. High concentrations of the hydrogen acceptor (acetone, up to 50% v/v) are tolerated by the enzyme. Examples for the enantio-, and regioselective oxidation of sec-alcohols employing ADH-‘A’ in the wild type strain as well as over-expressed ADH-‘A’ in E. coli are given.

Graphical abstractEmploying acetone as hydrogen acceptor various sec-alcohols can be oxidized to the corresponding ketone in an asymmetric fashion. The enzyme exhibits exclusive regioselectivity for secondary alcohols, primary alcohols remain untouched. This protocol does not only provide a simple ‘green’ oxidation method for organic synthesis at ambient conditions, but also allows the preparation of ketones, which are labeled ‘natural’ for flavor and fragrance applications. Figure optionsDownload full-size imageDownload as PowerPoint slide