Synthesis of indoloquinolines : an intramolecular cyclization leading to advanced Perophoramidine-relevant intermediates

Abstract

The bioactive natural product perophoramidine has proved a challenging synthetic target. An alternative route to its indolo[2,3-b]quinolone core structure involving an N-chlorosuccinimde mediated intramolecular cylization reaction is reported. Attempts to progress towards the natural product are also discussed with an unexpected deep-seated rearrangement of the core structure occurring during an attempted iodoetherification reaction. X-ray crystallographic analysis provides important analytical confirmation of assigned structures.