Synthesis of 2H,9H-naphtho[2,3-b:7,6-b']dipyran-2,9-diones as potential DNA-reactive agents

New 2H,9H-naphtho[2,3-b:7,6-b']dipyran-2,9-diones have been synthesized. The tetracyclic derivatives were obtained by two different synthetic pathways, both having, as a common intermediate, the 3,6-dihydroxynaphthalene-2,7-dicarboxaldehyde.