Synthesis and reactions of some new quinoline thiosemicarbazide derivatives of potential biological activity

Quinoline-2-carbohydrazide (3) was reacted with aryl or alkyl isothiocyanates to give the corresponding quinoline thiosemicarbazides (4a-e). Cyclization of the substituted thiosemicarbazides with sodium hydroxide led to the formation of 5-(quinolin-2-yl)-2H-1, 2, 4-triazole-3(4H)-thiones (5a-e). Desulfurization of thiosemicarbazides by mercuric oxide gave 5-(quinolin-2-yl)-1, 3, 4-oxadiazol- 2-amines (6a-e). Treatment of thiosemicarbazides with ethyl bromoacetate or α -bromopropionic acid yielded (Z)-N′-(3-substituted thiazolidin-4-oxo-2-ylidene) quinoline-2-carbohydrazides (7a-d), (8a-d), respectively. Treatment of thiosemicarbazides with chloroacetone furnished (Z)-N′-(4-methyl-3- substituted-thiazol-2(3H)-ylidene) quinoline-2-carbohydrazides (9a-d). Furthermore, the reaction of thiosemicarbazides with phosphorus oxychloride gave N-substituted-5-(quinolin-2-yl)-1,3,4-thiadiazol-2-amines (10a-e). All newly synthesized compounds were tested and evaluated for antimicrobial activity.