Oxidation of Phosphonocysteine and Phosphonohomocysteine. Synthesis of Phosphonocysteic and Phosphonohomocysteic Acids

The bromine promoted oxidations of phosphonocysteine and phosphonohomocysteine are described. The reactions were found to occur via S-bromination-hydrolysis sequence. The formation of cyclic intermediate - sulfonamide derivative of phosphonohomocysteic acid is proposed. The ultimate products of oxidations - phosphonocysteic and phosphonohomocysteic acids were isolated in high yields and characterized.