Antitumour polycyclic acridines. Part 10.1 Synthesis of penta- and hexa-cyclic heteroaromatic systems by radical cyclisations of substituted 9-anilinoacridines

9-Anilinoacridines substituted with a bromine atom in the 2-position of the anilino group or the 1-position of the acridine moiety can be cyclised with tributyltin hydride–AIBN to penta- or hexacyclic acridines. Of the polycyclic systems 13,14-dihydropyrrolo[3′,2′,1′:8,1]quino[4,3,2-kl]acridine 14a is the most potent cytotoxic agent displaying a mean GI50 concentration against a panel of 60 human tumour cell lines of 0.06 μM.