Trithiazyl trichloride 1 converts 1, 2, 5-triphenylpyrrole 5 into its 3, 4-dichloro derivative together with the isothiazole imine 6 and the imine hydrolysis product, the ketone 3. The best yield of the isothiazole 6 is obtained in the presence of 4 Å molecular sieves (Table 1). Conversion of the pyrrole 5 into the isothiazole 6 is exactly analogous to the reaction of 1 with 2, 5-diphenyl-furan and-thiophene. Other N-aryl and the related 2, 5-diphenylpyrroles ...
