Synthesis of Benzo[b]thiophene Substituted Carbamates,Ureas, Semicarbazides,and Pyrazoles and Their Antimicrobial and Analgesic Activity

2-Azidocarbonyl-3-chlorobenzob]thiophene 3 was obtained from 3-chloro-benzob]thiophene-2-carbonyl chloride 1 and 3-chloro-benzob]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, ¹ H NMR, and mass spectral data and have been screened for antimicrobial and analgesic activities.