FeBr 3 -catalysed synthesis of 3-aroylimidazo[1,2- a ]pyridine and 3,3'-(arylmethylene)bis(2-phenylimidazo[1,2- a ]pyridines) derivatives from 2-arylimidazo[1,2- a ]pyridines and aromatic aldehydes: an investigation about mechanistic insights.

In a new approach, a series of 3-aroylimidazo[1,2- a ]pyridine derivatives were prepared in high yields. This approach revealed the direct Fe-catalyzed functionalization of imidazo[1,2- a ]pyridine derivatives with aryl aldehydes via an aerobic oxidative cross-dehydrogenative coupling process. This transformation occurred in the presence of air, and FeBr 3 served as a homogeneous Lewis catalyst. O 2 was found to be the principal oxidant responsible for the method's success. Interestingly, when these reactions were carried out under an argon atmosphere, 3,3'-(arylmethylene)bis(2-phenylimidazo[1,2- a ]pyridines) derivatives were prepared in good yields.