Facile synthesis, characterization and pharmacological activities of 3,6-disubstituted 1,2,4-triazolo[3,4-b][1,3,4]thiadiazoles and 5,6-dihydro-3,6-disubstituted-1,2,4-triazolo[3,4-b][1,3,4]thiadiazoles

Two new series of compounds namely, 3,6-disubstituted-1,2,4-triazolo[3,4-b][1,3,4]thiadizoles (5a–j) and 5,6-dihydro-3,6-disubstituted-1,2,4-triazolo[3,4-b][1,3,4]thiadizoles (7a–j) were prepared. In continuation of a previously reported study, the first series (5a–j) were synthesized by the cyclocondensation of 4-amino-5-(2-bromo-5-methoxyphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (4) with various substituted aromatic carboxylic acids in phosphorus oxychloride and the second series (7a–j) by the reaction of (4) with various substituted aromatic aldehydes in the presence of p-Toluene sulfonic acid. Reaction of (4) with the aldehyde (9) afforded the Schiff's base (10) and not the cyclised product (11) on treatment with p-Toluene sulfonic acid. Synthesized compounds were structurally confirmed by spectral analysis and studied for their anti-inflammatory, analgesic, anti-oxidant and antimicrobial activities. Some of the tested compounds showed significant pharmacological activities.

Graphical abstractA series of 3,6-disubstituted-1,2,4-triazolo[3,4-b][1,3,4]thiadiazoles (5a–j), 5,6-dihydro-3,6-disubstituted-1,2,4-triazolo[3,4-b][1,3,4]thiadiazoles (7a–j) and triazolo Schiff's base (10) were prepared and evaluated for their anti-inflammatory, analgesic, anti-oxidant, antibacterial and anti-fungal activities.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► New series of 1,2,4-triazolo[1,3,4]thiadiazole derivatives were synthesized. ► All the newly synthesized compounds were characterized by spectral studies. ► Anti-inflammatory and analgesic study was performed. ► Antioxidant activity of the biologically active compounds was also tested. ► Anti-microbial evaluation of synthesized compounds was carried out.