Synthesis of imidazo[1,2-a]pyridines in a sequential one-pot Groebke-Blackburn modification using 2-aminopyridines, aldehydes and amines.

Herein we present a novel synthetic procedure for the synthesis of imidazo[1,2-a]pyridines in a modified Groebke-Blackburn fashion. In a sequential three-step one-pot protocol the commercially hardly available isocyanide-component is formed in situ using standard reagents. Cyclization to the desired products can be afforded in the same reaction mixture. The absent need of isolation of the isocyanide in this protocol eases its handling considerably and workup is only needed to finally furnish the imidazo[1,2-a]pyridines via coloumn chromatography. This protocol is a convenient way to more diverse libraries of imidazo[1,2-a]pyridines extending the functionality of the Groebke-Blackburn synthesis.