One pot synthesis of 4-iodo-3-phenylbenzo[ <i>b</i> ][1,6]naphthyridine via imino iodization-cyclization of alkynylquinoline-3-carbaldehydes

Simple, environmentally benign and metal free one pot strategy has been used for the synthesis of 4-iodo-3-phenylbenzo[b][1,6]naphthyridine from O-alkynylquinolinyl aldehydes with tert-butyl amine and iodine through imine formation in good to excellent yield at room temperature in aerobic and mild conditions. The beauty of this reaction is the imine formation and cyclization in the same reaction pot. Due to presence of iodine in product, it can be useful for further reaction and can be valuable synthon for new organic compounds.