Chloroperoxidase and hydrogen peroxide: An efficient system for enzymatic enantioselective sulfoxidations

High enantioselectivities were obtained in chloroperoxidase catalyzed oxidation of organic sulfides (99% ee in the case of methyl 2-pyridyl sulfide) with H2O2 in aqueous buffer solution, pH 5, at 25°C. The kinetic parameters in the oxidation of a series of sulfides both with H2O2 and tert-butyl hydroperoxide were determined and the data are consistent with enzymatic oxidation involving presumably a ternary complex. In all cases the reaction afforded the (R) sulfoxide as predominant or exclusive enantiomer.