1,9,8-cyclization of 1,8-disubstituted anthraquinones. 12H-benzo[m,n]chromeno [2,3,4-k, l]kacridine derivatives

Article abstract of DOI:10.1007/BF00552782

The cyclization of 1-(2,5-dihalophenylamino)-8-hydroxyanthraquinones or the corresponding 8-methoxycompounds in concentrated sulfuric acid has given derivatives of a new hexanuclear heterocyclic system -12H-benzo[m,n]chromeno [2,3,4-k, l]acridine. It has been shown that the double cyclization takes place initially through the closure of the pyridine ring with the formation of 9H-napth[3,2,1-k, l]acridine, the product of 1,9-cyclization. Under the reaction conditions the latter undergoes intramolecular aroxylation with the formation of a pyran ring under a-typical conditions.