Synthesis and antimicrobial activities of some new 1,2,4-triazole derivatives

Abstract

The synthesis of ethyl [3-(cyanomethyl)-5-alkyl-4H-1,2,4-triazol-4-yl] carbamates (2a-d) was performed starting from ethyl 2-[ethoxy(4-(aryl)methylene] hydrazinecarboxylates (1a, 1b). The treatment of 2a with thiosemicarbazide afforded ethyl [3-[(5-amino-1,3,4-thiadiazol-2-yl)methyl]-5-(4-nitrophenyl)-4H- 1,2,4-triazol-4-yl]carbamates (3a), whereas compound 2b produced 5-{[4-amino-5-(4-methylphenyl)-4H-1,2,4-triazol-3-yl]methyl}-1,3, 4-thiadiazol-2-amine (3b) in the same reaction conditions. The treatment of tertbutyl 2-[2-(4-chlorophenyl)-1-ethoxyethylidene]hydrazinecarboxylate (5) with malonohydrazide or cyanoacethydrazide gave the corresponding 1,2,4-triazol-ylcarbamate derivatives (6 or 9); then the hydrolysis of these compounds resulted in the formation of 3-{[4-amino-5-(4-chlorobenzyl)-4H-1,2,4- triazol-3-yl]methyl}-5-(4-chlorobenzyl)-4H-1,2,4-triazol-4-amine (7) and [4-amino-5-(4-chlorobenzyl)-4H-1,2,4-triazole-3-yl]acetonitrile (10), respectively. The synthesis of the Schiff base derivatives 3-(4-chlorobenzyl)-5- {[5-(4-chlorobenzyl)-4-[(2-hydroxyphenyl-methylene)amino]-4H-1,2,4-triazol-3-yl] methyl}-N-(2-hydroxyphenylmethylene)-4H-1,2,4-triazol-4-amine (8), and (5-(4-chlorobenzyl)-4-{[(2,6-dichlorophenyl)methylene]amino}-4H-1,2, 4-triazol-3-yl)acetonitrile (12) was performed from the reaction of compounds 7 and 10 with salicyl aldehyde (for 8) or 2,6-dichlorobenzaldehyde (for 12), respectively. The treatment of compounds 5 or 10 with thiosemicarbazide gave 5-{[4-amino-5-(4-chlorobenzyl)-4H-1,2,4-triazol-3-yl]methyl}-1,3, 4-thiadiazol-2-amine (11). All the newly synthesized compounds were screened for their antimicrobial activities and were found to possess good or moderate antimicrobial activity. © TÜBİTAK.