NBS mediated one-pot regioselective synthesis of 2,3-disubstituted imidazo[1,2-a]pyridines and their unambiguous characterization through 2D NMR and X-ray crystallography

A simple and mild protocol towards the regioselective synthesis of 1-aryl/heteroaryl-1-(2-methylimidazo[1,2-a]pyridin-3-yl)methanones has been developed by one-pot condensation of 2-aminopyridine with 1,3-diketones involving the intermediacy of 2-bromo-1,3-diketones formed in situ from 1,3-diketones using N-bromosuccinimide (NBS) in DCM by stirring at room temperature. The structure of the regioisomer has been confirmed unambiguously by the rigorous multinuclear NMR [(1H–13C) HMBC, (1H–13C) HMQC, (1H–15N) HMBC] spectroscopy and X-ray crystallographic studies.

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