Synthesis of novel chromeno[1,6]naphthyridine derivatives in PEG-400 via catalyst-free, one-pot, and multicomponent reactions

An efficient, one-pot, and catalyst-free pathway was reported for the synthesis of novel chromeno[1,6]naphthyridine derivatives via a multicomponent condensation reaction of salicylaldehyde derivatives, malononitrile dimer, and active methylene compounds. All the reactions were performed in polyethylene glycol-400 as a green solvent at 80 °C. The reactions proceeded with a high-atom economy, and new products were synthesized with good yields and a simple work-up procedure, with water as the only by-product.