Diorganodichalcogenides and their intramolecular cyclization reactions

Bis(2-acetylphenyl)dichalcogenides of type [2-(O=CMe)C6H4]2E2 (E=S, Se, Te) were prepared by the hydrolysis of [2-{(CH2O)2C(CH3)}C6H4]2E2. In their reaction with benzylamine these species yield an air-sensitive condensation product, which undergoes a fast, unexpected oxidative intramolecular cyclization. This process proved to be a very convenient way to prepare 3-amino substituted benzo[b]chalcogenophenes. By contrast, the reaction between [2-(O=CMe)C6H4]TeCl and benzylamine resulted in the condensation product [2-(C6H4CH2N=CMe)C6H4]TeCl.