Synthesis and antimicrobial activities of some new [1,2,4]triazolo[3,4-b] [1,3,4]thiadiazoles and [1,2,4]triazolo[3,4-b] [1,3,4]thiadiazines

Abstract

Acetic acid hydrazides containing 1,2,4-triazol-3-one ring (4a-d) were synthesized by the reaction of compounds 2a-k with hydrazine hydrate. (5-Mercapto-1,3,4-oxadiazol-2-yl)methyl-2,4-dihydro-3H-1,2,4-triazol-3-one derivatives (5a-d) were obtained from the reaction of compounds 4a-d with carbon disulfide in the presence of KOH. The treatment of compounds 5ad with hydrazine hydrate led to the conversion of 1,3,4-oxadiazole ring to amino-1,2,4-triazole ring in compounds 6a-d. A second method involving the reaction of compounds 7a-d with thiocarbohydrazide also gave the same products, 6a-d. The condensation of compounds 6a-d with acetic acid produced 5-alkyl-4-amino-2-[(6-methyl[1,2,4] triazolo[3,4-b][1,3,4]thiadiazol-3-yl)methyl]-2,4-dihydro-3H-1,2, 4-triazol-3-ones (8a-d) while its condensation with carbon disulphide or formic acid afforded 5-alkyl-4-amino-2-[(6-mercapto[1,2,4]triazolo[3,4-b][1,3,4] thiadiazol-3-yl)methyl- (9a-d) and 5-alkyl-4-amino-2-{([1,2,4]triazolo[3,4-b][1, 3,4]thiadiazol-3-ylmethyl)}-2,4-dihydro-3H-1,2,4-triazol-3-ones (10a-d), respectively. On the other hand, the synthesis of 5-alkyl-4-amino-2-[(6-phenyl- 7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-3-yl)methyl]-2,4-dihydro-3H-1,2, 4-triazol-3-ones (11a-d) were performed by the treatment of compounds 6a-d with á-bromo acetophenone. © ARKAT.