Formation of new heterocycles by intramolecular cyclization reactions of alkynethiolates with nitrogen nucleophiles

1,2,3-Thiadiazole-4-carbohydrazides undergo base-catalyzed ring cleavage with liberation of nitrogen and recyclization to 5-thiopyrazolones, 6-thiomethylidene-1,3,4-oxadiazin-5-ones or 5-thio-7H-pyrazolo[5,1-b][1,3]thiazine-2,7-diones.