Synthesis of Some Mannich Bases and Novel Benzofuran Derivatives Containing Imidazo[2,1-b][1,3,4]thiadiazoles as Biological Agents

Abstract

An efficient route for the synthesis of 6-(1-benzofuran-2-yl)-2-phenyl imidazo[2,1-b] [1,3,4] thiadiazole(4a-e), was achieved by the reaction of 1-(1-benzofuran-2-yl)-2-bromoethanone (2) with 5-aryl-1,3,4-thiadiazol-2-amine(3-ae). The reaction mixture containing compound 4d with secondary amines and formaldehyde with catalytic amount of acetic acid, furnished corresponding Mannich bases (5-7). All newly synthesized compounds were screened for analgesic and antimicrobial activity. Among all the compounds tested for antibacterial activity, compound 7 showed significant activity against S. aureus when compared to other compounds, compound 4a, 4d and 5 exhibited highest activity against B. subtilis, compound 4b, 4d and 7 exhibited equipotent activity against K. pneumoniae and compound 6 exhibited promising activity against E. coli comparable with the standard drug Tetracycline. Among all the compounds tested for antifungal activity, the compound 4b and 4c exhibited significant activity against A. niger, compound 4c and 4e showed highest activity against C. albicans, compound 7 exhibited promising activity against P. chrysozenous and compound 4a and 4b exhibited highest activity against T. vridar as compared with standard drug Flucanozole. Compound 4b and 4d proved to be potent analgesic agents, as they exhibited significant analgesic activity comparable to standard drug and the remaining compounds showed moderate activity as compared to standard drug. Keywords: 2-Acetylbenzofuran, Mannich bases, imidazo[2,1-b][1,3,4]thiadiazole, analgesic and antimicrobial activity