Synthesis of condensed sulfur- and nitrogen-containing heterocycles via polar cycloaddition of hetarene sulfenyl chlorides to a C–C multiple bond

The reactions of HetSCl, where Het = 4,6-dimethyl-2-pyrimidyl, 3-methoxycarbonyl-2-pyridyl, 1,3-benzothiazol-2-yl and 8-quinolyl, with a carbon–carbon multiple bond in the LiClO₄–MeNO₂ system lead to the formation of products of polar cycloaddition of sulfur-containing electrophile with ring closure by the nitrogen atom of the HetS fragment.