Organic Heterocyclothiazenes. Part 19. Synthesis of 1,3,2-Dithiazoles Using Bis(chlorothiio)nitronium Tetrachloroaluminate, [N(SCl)2][AlCl4

Abstract

Reaction of the readily prepared bis(chlorothio)nitronium tetrachloroaluminate (4) with electron-rich arylacetylenes in dichloromethane at room temperature leads to a cycloaddition reaction resulting in 4-aryl-1,3,2-dithiazolium salts (5) which when treated in situ with base afford 5-aryl-1,3,2-dithiazole-4-thiones (6). The scope of this reaction with other alkenes and alkynes is described. No reaction was observed with the electron-deficient 4nitrophenylacetylene. The conjugated thione (17) was also formed in the reaction of an old specimen of salt (4) with phenylacetylene. Treatment of salt (4) with 1,2-dichloroethylene followed by aniline gave a minor amount of the novel dimer (20). The reaction of acetophenone oxime with disulfur dichloride provides a route to the salt (26) which on treatment with water or aniline affords 4-phenyl-1,2,3-dithiazol-5-one (23) and 4-phenyl-5-phenylimino-1,2,3-dithiazole (27) respectively. 14 N NMR studies are shown to be useful in distinguishing between 1,2,3- and 1,3,2-dithiazoles. X-Ray crystal structures are presented for compounds (17,20,27), and 5-anilino-1,3,2-dithiazole-4-thione