Microwave-Assisted Synthesis of New Schiff Bases from Imidazo[1,2-a]pyridine-3-carbaldehyde and Aromatic Amines in PEG-400 as a Green Approach

We have developed a short and highly efficient microwave-enhanced protocol for the synthesis of new Schiff bases, ( E )- N -[(2-arylimidazo[1,2- a ]pyridine-3-yl)methylidene]pyridin-2-amines, by the condensa­tion of 2-arylimidazo[1,2- a ]pyridine-3-carbaldehydes with 2-aminopyridine in polyethylene glycol-400 as a green reaction medium in the presence of a catalytic amount of acetic acid. The essential features of this protocol are enhanced reaction rate, more eco-friendly reaction conditions, high yields, and green aspects such as avoiding toxic catalysts and hazardous organic solvents and reuse of the reaction medium.