Asymmetric oxidations at sulfur catalyzed by engineered strains that overexpress cyclohexanone monooxygenase

Recombinant strains of baker's yeast (Saccharomycescerevisiae) and Escherichiacoli expressing cyclohexanone monooxygenase from Acinetobacter sp. NCIB 9871 have been used as whole-cell biocatalysts for oxidations of several sulfides, dithianes and dithiolanes to the corresponding sulfoxides. The enantio- and diastereoselectivities of these reactions compare favorably with oxidations catalyzed by the purified monooxygenase or the parent microorganism (a class II pathogen). The facility of handling yeast reactions makes these biotransformations an attractive alternative route to optically pure sulfoxides.