Ionic Liquid Promoted Facile One-Pot Synthesis of 1-Pyridylimidazo[1,5-a]pyridines from Dipyridylketone and Aryl Aldehydes

A highly efficient one-pot methodology has been developed to synthesize a class of substituted l-pyridylimidazo[1,5-a]pyridines, using Bronsted acidic ionic liquid 1-butylimidazolium tetrafluoroborate, [Hbim]BF 4 in excellent isolated yields in the absence of any catalyst. The methodology is characterized by simple work-up procedures along with efficient recovery and recycling of the ionic liquid, which acts as a reaction medium as well as a promoter.