The reaction of several alpha-chloroarylhydrazones, 2, with thioacetam
ide or a thioacetamide-thiobenzamide mixture in refluxing toluene affo
rds stituted-2,3-dihydro-3-aryl-2-(thioacyl)methylene- 1,3,4-thiadiazo
les, 5. Two 1,6-dithia-3,4-diazaspiro[4.4]nona-2,8-diene derivatives (
6)and a 1,3,4-thiadiazepine derivative (7) obtained as by-products are
the first examples of these heterocyclic systems.