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.