Lewis Acid Promoted Synthesis of Imidazopyridinyl-1,3,4-Oxadiazole Hybrids with Antibacterial Potential

A simple and efficient Lewis acid–assisted synthetic strategy has been developed for the preparation of a new series of imidazopyridinyl-1,3,4-oxadiazole derivatives. The approach involves cyclodehydration of 2-phenylimidazo[1,2-a]pyridine-3-carbohydrazide with various aromatic and heteroaromatic acid chlorides using boron trifluoride diethyl etherate (BF₃·Et₂O) as a cyclization promoter. The reactions proceed smoothly under mild conditions to afford the desired heterocyclic hybrids in good to excellent yields (79–86%). All synthesized compounds were structurally characterized by IR, ¹H NMR, ¹³C NMR, and mass spectrometry. The antibacterial activity of the synthesized derivatives was evaluated against Escherichia coli and Staphylococcus aureus using the cup plate diffusion method. Several compounds exhibited appreciable antibacterial activity compared with streptomycin. Preliminary structure–activity relationship studies indicate that electron-donating and halogen substituents significantly influence antibacterial potency. The present study highlights imidazopyridinyl-1,3,4-oxadiazoles as promising scaffolds for antimicrobial drug development.