DABCO-catalyzed highly regioselective synthesis of novel 4H-pyrano[2,3-b]quinoline derivatives: One-pot three-component reaction

A regioselective synthesis of 4H-pyrano[2,3-b]quinoline derivatives via DABCO-mediated Knoevenagel condensation/heterocyclization sequence has been executed. In this way some new fused heterocyclic compounds were synthesized from 2-chloroquinoline-3-carbaldehyde as a versatile and efficient synthetic building block. The one-pot three-component reaction of 2-chloroquinoline-3-carbaldehyde and diverse cyclic active methylenes for construction of highly substituted quinolines scaffold has been accomplished under mild condition. The strategy included herein shows significant advantages, including a facile process with easy purification, excellent yields, wide applicability, available substrates, and cost-effective/eco-friendly solvent and catalyst.