Synthesis of benzo[b]thiophene substituted carbamates, ureas, semicarbazides, and pyrazoles and their antimicrobial and analgesic activity

Article abstract of DOI:10.1080/10426500802388433

2-Azidocarbonyl-3-chlorobenzo[b]thiophene 3 was obtained from 3-chloro-benzo[b]thiophene-2-carbonyl chloride 1 and 3-chloro-benzo[b]thiophene- 2-carboxy hydrazide 2. The compound 3 on Curtius rearrangement with various alcohols, amines, and hydrazines afforded the corresponding carbamates 4a-b, ureas 5a-j, and semicarbazides 6a-g, respectively. Compound 2 was also utilized for the synthesis of pyrazoles 7a-c by treatment with various chalcones. The structures of the newly synthesized compounds were elucidated on the basis of IR, 1H NMR, and mass spectral data and have been screened for antimicrobial and analgesic activities.