Abstract Acyl chlorides reacted with ammonium thiocyanate and carbonic dihydrazide under phase??transfer catalysis to first afford 2, 2′??bis (acylaminothiocarbonyl)??carbonic dihydrazides, which further cyclized in the presence of glacial acetic acid to efficiently give 1?? (5′??acylamino??1′, 3′, 4′??thiadiazol??2′??yl)??4??acyl??thiosemicarbazides in high yield.
