Antitumour polycyclic acridines. Part 13. Synthesis of 2-substituted 7H-pyrido[4,3,2-kl]acridines by thermolysis of 9-(5-alkyltriazol-1-yl)acridines

Abstract

Interaction of phosphoranylidene ketones with 9-azidoacridine in refluxing benzene affords 9-(5-substituted triazol-1-yl)acridines, which, on thermolysis in boiling diphenyl ether at 259 °C, yield 2-substituted 7H-pyrido[4,3,2-kl] acridines in high yields. These tetracyclic acridines are less potent inhibitors of human tumour cells in vitro than their pentacyclic analogues.