Xanthones in heterocyclic synthesis. An efficient and general route for the synthesis of regioselectively substituted phthalazines

Article abstract of DOI:10.3987/COM-11-12168

Xanthone undergoes regioselective substitution and nucleophically - triggered ring opening to the corresponding ketone. Hydrazone of the latter oxidatively rearranges to ortho-diacylarenes, which, then, with hydrazine gives regioselectively substituted phthalazines. Molecular modeling analysis and 1HNMR spectra indicate an intramolecular H-bonding engaging phenol OH and phthalazine N-3 atom.