Abstract 3-Aminocoumarin undergoes the Skraup reaction to give a new ring system, 5H [l] benzo-pyrano [3, 4-b] pyridin-5-one (IVa). When 3-aminocoumarin was condensed with the ethoxy methylene derivatives of active methylene compounds, ethyl acetoacetate, and dimethyl acetylenedicarboxylate, the intermediates Vla-VIf were formed which on thermal cyclizations afforded other derivatives of 5H [l] benzopyrano [3, 4-b] pyridin-5-one (IVb-IVf) ...