Abstract The synthesis of a new heterocylic ring system is reported. The condensation of 9, 10-dihydro-9-oxo-4-acridine carboxamide (7) with diethoxymethyl acetate gave pyrimido [5, 6, 1-d, e] acridine-3, 7-dione (8). The amide 7 reacts with ethyl chloroformate to afford 2H- pyrimido [5, 6, 1-d, e] acridine-1, 3, 7-trione (9).
