Chloroperoxidase-catalyzed oxidation of methionine derivatives

Treatment of N-methoxycarbonyl C-carboxylate ester derivatives of L- and D-methionine and L-ethionine by chloroperoxidase-hydrogen peroxide resulted in oxidation at sulfur to produce the (R-S) sulfoxide in moderate to high diastereomeric excess. The (R-S) sulfoxide of methionine was also obtained in moderate to high diastereomeric excess from (+/-)(SO)-N-methoxycarbonyl-L-methionine methyl ester sulfoxide by ester hydrolysis using alpha-chymotrypsin, Aspergillus sp. protease or subtilisin Carlsberg.