Synthesis, characterization and antimicrobial activities of poliheterocyclic compounds containing 1,2,4-triazol-3-one ring

In this study, some 1,2,4-triazol-3-one derivatives (71, 74, 75) were synthesized and then converted to the corresponding acid hydrazides (79-81) via the formation of ester derivatives (76-78). The treatment of hydrazides (79-81) with CS2 afforded 1,2,4-triazol-3-one derivatives also containing 1,3,4-oxadiazole nucleus (82-84). The synthesis of the corresponding Mannich bases (86, 87) was performed starting from 82 via the formation of the corresponding Schiff base (85). Arilmethylidenacetohydrazides (88-100) were obtained from the reaction of hydrazides (79-81) with several aldehydes. Carbonothioyl derivatives (101-103) were obtained from the reaction of 79-81 with phenylisothiocyanate; and then converted to the compounds containing 4-phenyl-5-sulfanyl-4H-1,2,4-triazol-3-yl)methyl]-2,4-dihydro-3H-1,2,4-triazol-3-ones (104, 105) and [5-(phenylamino)-1,3,4-thiadiazol-2-yl]methyl-2,4-dihydro-3H-1,2,4-triazol-3-ones (106, 107) in basic or acidic media. Two alkylated derivatives (108, 109) of 104 were obtained in basic media using methyl iodide or 1-Bromoheptane. Moreover, compound 104 were converted to a schiff base (110) containing 4-methoxybenzaldehyde. The treatment of the compounds containing both 1,3,4-oxadiazole and 3H-indol moieties (83, 84) with hydrazine hydrate resulted the conversion of 1,3,4-oxadiazol ring into 4-amino-1,2,4-triazole ring. Finally, the treatment of hydrazides (80, 81) with 3-chloro- or 3-bromobenzensulfonylchloride yielded the corresponding N'-(4-halogenophenylsulfonyl) acetohydrazide (113-115) derivatives.The structures of newly synthesized compounds were confirmed by IR, 1H NMR, 13C NMR and Mass spectroscopic techniques. Antimicrobial properties were screened by Assoc. Prof. Şengül Alpay Karaoğlu (Rize Univ. Department Biology).