Practical two-step synthesis of an enantiopure aliphatic terminal (S)-epoxide based on reduction of haloalkanones with Designer Cells

A practical biocatalytic method for the synthesis of aliphatic P-halogenated (S)-alcohols as epoxide precursors by means of an enantioselective reduction of the corresponding ketones with recombinant whole cells, bearing an alcohol dehydrogenase and a glucose dehydrogenase, was developed. The biotransformations operate at high substrate concentrations of up to 208 g/L, and afford the (S)-beta-halohydrins with both high conversions of > 95 % and enantioselectivities of > 99 % ee. Base-induced cyclization of the P-halohydrin intermediates gave the desired (S)-epoxides in high yield and enantiomeric purity (> 99 % ee).