Synthesis of 2,3,5-Trisubstituted 1,3,4-Oxadiazole Via Cyclization of 5-Fused Heteryl Pyrazole-3-Carbohydrazone having Quinolin-3-yl Moiety and their Antibacterial Activity

In the undertaken research, 5-(5-H/Br benzofuran-2-yl)-N'-((-2-(p-tolyloxy) substituted quinolin-3-yl)methylene)-1-phenyl-1H-pyrazole-3-carbohydrazide (3a-h)  on treatment with acetic anhydride afforded novel 1-(5-(5-(5-H/Br benzofuran-2-yl)-1-phenyl-1H-pyrazol-3-yl)-2-(-2-(p-tolyloxy)substitutedquinolin-3-yl)-1,3,4-oxadiazol-3(2H)-yl)ethanone derivatives (4a-h). 5-fused heteryl pyrazole-3-carbohydrazone (3a-h) needed  for the synthesis of  4a-h were synthesized by reaction of 2-(p-tolyloxy) substituted quinoline-3-carbaldehyde (2a-h) with 5-(5-H/Br benzofuran-2-yl)-1-phenyl-1H-pyrazole-3-carbohydrazides (1a-b) in ethanol as solvent. The structures of the newly synthesized compounds were identified on the basis of elemental analysis and spectral studies like IR, 1H NMR and Mass spectra. The in-vitro antibacterial screening of these synthesized compounds against E. coli, S. aureus, E. areogenes and B. thurengienesis relative to the reference standard Chloramphenicol have been found to possesses good to moderate inhibitory activity.