Biocatalytic oxidation of S-alkylcysteine derivatives by chloroperoxidase and Beauveria species

Treatment of N-methoxycarbonyl C-carboxylate ester derivatives of S-methyl-l-cysteine by chloroperoxidase (CPO)/hydrogen peroxide resulted in oxidation at sulfur to produce the (RS) sulfoxide in moderate to high diastereomeric excess (DE). The (SS) natural product sulfoxide chondrine was obtained via biotransformation of the N-t.boc derivative of l-4-S-morpholine-2-carboxylic acid using Beauveria bassiana or Beauveria caledonica.