1-Acylthiosemicarbazides, 1,2,4-triazole-5(4H)-thiones, 1,3,4-thiadiazoles and hydrazones containing 5-methyl-2-benzoxazolinones: Synthesis, analgesic-anti-inflammatory and antimicrobial activities Original Research Article

Acetic acid hydrazide containing 5-methyl-2-benzoxazolinone (4) was synthesized by the condensation of 2-(5-methyl-2-benzoxazolinone-3-yl)acetate with hydrazine hydrate. Thiosemicarbazide derivatives (5a–5d) were afforded by the reaction of corresponding compound 4 with substituted isothiocyanates. The cyclization of compounds 5a–5d in the presence of triethylamine resulted in the formation of compounds 6a–6d containing 1,2,4-triazole ring. On the other hand, the treatment of compounds 5a–5d with orthophosphoric acid caused the conversion of side chain of compounds 5a–5d into 1,3,4-thiadiazole ring: thus, compounds 7a–7c were obtained. The treatment of compound 4 with aromatic aldehydes resulted in the formation of arylidene hydrazides as cis–trans conformers (8a–8e). The structures of the compounds were elucidated by spectral and elemental analysis. While most compounds were exhibiting high activity in the analgesic-anti-inflammatory field, most of them were found to be inactive against bacteria and fungi.