Synthesis and antimicrobial activities of some new biheterocyclic compounds containing 1, 2, 4-triazol-3-one and 1, 3, 4-thiadiazole moieties

Abstract

2-(4-Amino-3-(4-chlorophenyl)-5-oxo-4, 5-dihydro-1 H-1, 2, 4-triazol-1-yl)-N'-[(2, 6 dihalogenophenyl)-methylene]acetohydrazides (3a, b) was obtained via the formation of 2-(4-amino-3-(4-chlorophenyl)-5-oxo-4, 5-dihydro-1 H-1, 2, 4-triazol-1-yl)acetohydrazide (2), which was obtained starting from 4-amino-5-(4-chlo-rophenyl)-2, 4-dihydro-3H-1, 2, 4-triazol-3-one (1) in 2 steps. 2-{[4-amino-3-(4-chlorophenyl)-5-oxo-4, 5-dihydro-1H-1, 2, 4-triazol-1-yl]acetyl}-N-phenylhydra-zine carbothioamide (4), which was prepared starting from 2, was converted to the corresponding 1, 3, 4-thiadiazole derivative (5) in acidic media. Moreover, the basic treatment of 4 resulted in the formation of 4-amino-5-(4-chlorophenyl)-2-[(4-phenyl-5-thioxo-4, 5-dihydro-1H-1, 2, 4-triazol-3-yl)methyl]-2, 4-dihydro-3H-1, 2, 4-triazol-3-one (7). The reactions of compounds 5 and 7 with methyl iodide in the presence of sodium ethoxide afforded the corresponding N-methyl (6) and S-methyl (8) derivatives, respectively. The synthesis of Mannich bases (10a and 10b) was performed from the reaction of 7 with morpholine or piperazine in the presence of formaldehyde. All the newly synthesized compounds were screened for their antimicrobial activity. The antimicrobial activity study revealed that compounds 3a, 3b, and5 showed good antimicrobial activities against the test microorganisms as compared with ampicillin. © tübi?tak.