ZnCl2 catalyzed efficient synthesis of 1,3,4-oxadiazole and 1,3,4-thiadiazole

New methods for the synthesis of 1,3,4-oxadiazole and 1,3,4-thiadiazole have been described. No cyclizations took place in the absence of ZnCl2. 1,3,4-Thiadiazoles are formed in the presence of ZnCl2 alone, whereas oxadiazoles are produced when a base such as Et3N or KOH was used along with ZnCl2. % Yields are optimized.