Synthesis of novel heterocycles from thiazolecarbohydrazides

Cyclization of 2-methyl (or -phenyl)-5-phenylthiazole-4-carbohydrazides (1) and (2) under various conditions gives differing oxadiazoles: 2-(2-substituted-5-phenyl-4-thiazolyl)-1,3,4-oxadiazole-5-thiones (7) and (8), and 2-(2-substituted-5-phenyl-4-thiazolyl)-1,3,4-oxadiazoles (9) and (10). Cyclodehydration of thiazolecarbonyl-thiosemicarbazides (3)–(6) with NaOH givesthe 3-(2-substituted-5-phenyl-4-thiazolyl)-4-substituted-4H-5-mercapto-1,2,4-triazoles (11)–(14), while H₃PO₄ gives the 2-(2-substituted-5-phenyl-4-thiazolyl)-5-phenylamino-1,3,4-thiadiazoles (15) and (16).A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Science Center, Russian Academy of Sciences, 420083 Kazan'. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 679–683, March, 1992.