Photochemical reactions of benzothiazole-2-thiones

Abstract

The photochemical reactions of benzothiazole-2-thiones in the presence of alkenes have been examined. Irradiation of N-unsubstituted benzothiazole-2-thione in the presence of electron-poor alkenes gave 2-substituted benzothiazoles. Irradiation of N-substituted benzothiazole-2-thiones and electron-poor alkenes yielded 2-alkylidenebenzothiazoles and the unexpected spiro-1,3-dithianes. The formation of these photoproducts can be explained in terms of the intermediacy of aminospirothietanes, which are derived by [2 + 2] photocycloaddition of the CS bond of benzothiazole-2-thiones to the CC bond of alkenes.