A one-pot, pseudo four-component synthesis of novel benzopyrano[2,3-b]pyridines under solvent-free conditions

A facile, one-pot, pseudo four-component catalyst- and solvent-free synthesis of novel benzopyrano[2,3-b]pyridines is achieved by Michael addition of various naphthols to iminocoumarin derivatives obtained from Knoevenagel condensation of salicylaldehydes with malononitrile, which can be attacked by another molecule of malononitrile to afford the title products. The advantages of this procedure are mild reaction conditions, high yields of products, generality, short reaction times and operational simplicity.