A ring opening reaction of benzisothiazolones. A new route to unsymmetrical disulfides

A series of unsymmetrical disulfides has been prepared by employing a reaction involving a ring opening, nucleophilic attack of a thiol on a 1,2‐benzisothiazol‐3‐one. The benzisothiazolones were in turn prepared by an intramolecular ring closure of an amide on a sulfenyl thiocarbonate. The sulfenyl esters were synthesized as intermediates for preparing mixed‐disulfides, but the benzisothiazolone ring closure occurred spontaneously. It was initially thought that the mixed‐disulfides were being formed from the sulfenyl ester, but the isolation and stepwise reaction of the benzisothiazolones provided proof for the reaction mechanism.