SYNTHESIS AND HETEROCYCLIZATION OF 2-CINNAMYLSULFONYLBENZOTHIAZOLE-1,1-DIOXIDE

We performed the synthesis and heterocyclization process of 2-cinnamylsulfonylbenzothiazole-1,1-dioxide. It was found that the oxidation of 2-cinnamylthiobenzothiazole with hydrogen peroxide in the presence of ammonium tungstate in ethanol results in the oxidation of both the exocyclic sulfur atom and the endocyclic thiazole sulfur, yielding 2-cinnamylsulfonylbenzothiazole-1,1-dioxide. The formation of this oxidation product is evidently can be explained by the change of the process catalyst from a molybdate to ammonium tungstate. To determine how changes in the electron density of the alkenyl substituent and the thiazole ring affect the course of haloheterocyclization, the bromination of 2-cinnamylsulfonylbenzothiazole-1,1-dioxide was carried out in chloroform at room temperature. It has been established that the bromine-induced heterocyclization of 2-cinnamylsulfonylbenzothiazole-1,1-dioxide results in the annulation of a thiazine ring, yielding 3-bromo-4-phenyl-3,4-dihydro-2H-[1,3]thiazino[2,3-b][1,3]benzothiazolium-1,1,10,10-tetraoxide tribromide in moderate yield; this result is consistent with the halogenation of 2-cinnamylthiobenzothiazole. It is shown that changes in the electron density of the cinnamylthio substituent and the thiazole ring do not affect the course of the halo-heterocyclization.