Selective Oxidation of Unsymmetrical Thiosulfinic S-Esters to the Corresponding Thiosulfonic S-Esters with NaIO4

Unsymmetrical thiosulfinic S-esters were oxidized with sodium metaperiodate in aqueous media to the corresponding unsymmetrical thiosulfonic S-esters nearly quantitatively. The oxidation was accelerated by addition of a catalytic amount of inorganic and organic acids or halogen. Sulfinic esters were produced competitively along with the thiosulfonic S-esters in the oxidation of thiosulfinic S-esters in aqueous alcohol. However, unsymmetrical disulfides were not oxidized selectively to the corresponding unsymmetrical thiosulfonic S-esters but a mixture of both symmetrical and unsymmetrical thiosulfonic testers was obtained.