Green synthesis of 5-methylpyridinium derivatives by C2-functionalization of pyridine-1-oxide derivatives and their antibacterial activity

An innovative green economic route has been developed for one pot multicomponent synthesis of 5-methylpyridinium derivatives by the reaction of 3-methylpyridine-1-oxide, aromatic aldehyde and β-ketoester catalysed by different ionic liquids (ILs), [BMIM][OH], [BMIM][Cl], [BMIM][Ac] in good to excellent yields. A relative study reinforced that [BMIM][OH] is the best IL for this C2-functionsalization reaction. The main highlights of this synthetic protocol are simple work-up, cost effectiveness and environmentally benign processing. The synthesized derivatives have been assessed for possible antibacterial activity against Staphylococcus aureus and Escherichia coli by using the microdilution method. The results of antibacterial activity suggests that compound 4I shows best antibacterial activity and other compounds show good to moderate activity.