An eco-friendly sequential catalyst- and solvent-free four-component stereoselective synthesis of novel 1,4-pyranonaphthoquinones

A series of novel highly functionalized 1,4-pyranonaphthoquinones has been synthesized stereoselectively from one-pot sequential reactions of anilines, diethyl acetylenedicarboxylate, 2-hydroxynaphthalene-1,4-dione and benzaldehydes under microwave irradiation. This solvent-and catalyst-free transformation affording biologically relevant heterocycles presumably involves two Michael additions, aldol condensation and annulation reactions.