Synthesis of indolo[4,3-bc]phenanthridine-6,11(2H,12H)-diones using the schiff base–homophthalic anhydride cyclization reaction

ABSTRACT

A novel indolophenanthridine ring system has been synthesized via the Schiff base–homophthalic anhydride cyclization followed by thionyl chloride–mediated dehydrogenation and intramolecular Friedel–Crafts acylation. This adds to the array of heterocyclic systems that are available through the cycloaddition reaction of imines with cyclic dicarboxylic acid anhydrides. The cytotoxicities of the indolophenanthridines were investigated in human cancer cell cultures, and the results documented significant antitumor activity in a variety of human cancer cell lines. This provides a new heterocyclic scaffold for anticancer drug design.

GRAPHICAL ABSTRACT

KEYWORDS:

• Anticancer
• cytotoxicity
• homophthalic anhydride
• indolophenanthridine
• Schiff base