The chemistry of a ketene‐sulfur dioxide adduct

Abstract

Abstract We have demonstrated the formation of a reactive species from ketene and sulfur dioxide and have investigated some of its reactions. The 3 + 2 ← 5 cycloaddition reactions of this intermediate with benzylideneaniline and its derivatives gave the corresponding 2,3‐diphenylthiazolidin‐4‐one 1,1‐dioxides. The reduction of 2,3‐diphenylthiazolidin‐4‐one 1,1‐dioxide with lithium aluminum hydride yielded the corresponding thiazolidine. Aniline and its derivatives reacted with the ketene‐sulfur dioxide adduct to give thioaceto‐1,3‐dianilide 3‐oxide. o ‐Phenylenediamine gave [2,1,5]benzothiadiazepin‐4‐one 2‐oxide, a derivative of a new ring system, [2,1,5]benzothiadiazepine. o ‐Aminophenol yielded [1,2,5]benzothiazepin‐4‐one 2‐oxide.