Synthesis of (Z)-hetarylmethylene and (Z)-substituted benzylidene derivatives of 4H-benzo[1,4]thiazine-3-thiones and their subsequent conversion to benzothiopyrano-[3,2-b][1,4]benzothiazines

Z)-Hetarylmethylene and (Z)-substituted benzylidene derivatives of 4H-benzo[1,4]thiazine-3thiones were prepared by the reaction of 4H-benzo[1,4]thiazine-3-thiones with various aldehydes.Subsequent treatment of the thiazine-3-thiones with dimethyl acetylenedicarboxylate and various arynes gave the corresponding dimethyl-4-aryl-4,10-dihydrothiopyrano[3,2b]benzothiazine-2,3-dicarboxylates and 12-aryl-6,12-dihydro-2,3-dimethoxy[1]benzothio pyrano[3,2-b][1,4]benzothiazines, respectively.