In(OTf)3 assisted synthesis of β-carboline C-3 tethered imidazo[1,2-a]azine derivatives

Synthesis of beta-carboline based natural products and synthetic derivatives is one of the frontier areas of research owing to their medicinal properties. It is envisaged that 3-formyl-9H-beta-carboline is a potential precursor and offers new vistas for the construction of a variety of heterocyclic architectures at the C-3 position of the beta-carboline skeleton. In this context, an efficient protocol has been developed for the synthesis of beta-carboline C-3 tethered imidazo[1,2-a] pyridine, imidazo[1,2-a] pyrimidine, and imidazo[1,2-a]pyrazine derivatives via exploration of the Groebke-Blackburn-Bienayme (GBB) reaction. The present protocol offers several advantages like operational simplicity, high atom economy, appreciable structural diversity and easy purification procedure.