Reduction, Mannich reaction and antimicrobial activity evaluation of some new 1,2,4-triazol-3-one derivatives

摘要

Ethyl[4-arylmethyleneamino-3-(4-metylphenyl)-5-oxo-4,5-dihydro-1H-1,2,4-triazole-1-yl]acetates (3a-e and 10a-d) were obtainedstarting from 4-amino-2,4-dihydro-3H-1,2,4-triazol-3-ones (1 and 9) in2 steps. The treatment of 3a-e with NaBH_4 resulted in the formationof 3 kinds of product incorporating carboxcilic acid (4a-c) or alcohol(5a-e) functionality. [4-{[(4-Methoxyphenyl)methylene]amino}- and4-{[pyridin-4-ylmethylene]amino}-3-(4-methylphenyl)-5-oxo-4,5-dihydro-1H-1,2,4-triazole-1-yl] acetic acids (6a, 6e) were obtained by thehydrolysis of the corresponding esters (5a-5e). The treatment of 6awith NaBH_4 caused the reduction of only the imine bond; the carboxylgroup remained unchanged. Then this carboxylic acid was converted tothe corresponding hydrazide (8) in 2 steps by reaction with ethanoland hydrazine hydrate, respectively. The synthesis of Mannich baseswas performed by the reaction of the corresponding 1,2,4-triazolescontaining an imine group (10a-d) with several primary or secondaryamines including morpholine or piperazine nucleus.All newly synthesized compounds were screened for their antimicrobial activity. The antimicrobial activity study revealed that the Mannich bases (11-16) showed good activity against the test microorganisms as compared with ampicillin.