Thiobenzohydrazides and dithiocarbazates in the synthesis of new 1,3,4-thiadiazine and 1,3,4-thiadiazole derivatives

Abstract

We previously reported on reactions of aromatic and heteroaromatic acid hydrazides with oxalyl chloride in boiling benzene, which afforded 80–90% of the corresponding 2-aryl(hetaryl)-4H-1,3,4-oxadiazine5,6-diones [1]. Analogous 4H-1,3,4-thiadiazine-5,6diones IIIa–IIIf were synthesized by reaction of carbothiohydrazides Ia–Ie and S-methyl-3-phenyldithiocarbazate (If) with 10–15% excess of oxalyl chloride (II) in anhydrous inert solvents (benzene, chloroform, carbon tetrachloride). The yields of thiadiazines IIIa–IIIf were 80–94%.