The reaction of 2-methylbenzothiazole or 2,5-dimethylbenzothiazole with dimethyl acetylene-dicarboxylate in the presence of heterocyclic compounds containing an NH group such as maleimide, succinimide, indole, 2-methyl indole and carbazole, leads to dimethyl 2-(2-methylenebenzo[d]thiazol-3(2H)-yl) succinate derivatives in good yields. The reactions proceed smoothly at room temperature without a catalyst.