Photocatalytic Synthesis of Polycyclic Indolones.

We report herein a photocatalytic strategy for a rapid and modular access to polycyclic indolones starting from readily available indoles. This strategy relies on the use of redox-active esters in combination with an iridium-based photocatalyst under visible light irradiation. The generation of alkyl radicals through decarboxylative single electron reductions enables intramolecular homolytic aromatic substitutions with a pending indole moiety to afford pyrrolo- and pyridoindolone derivatives under mild conditions. Furthermore, we demonstrated that these radicals could also be engaged into cascades consisting of an intermolecular Giese-type addition followed by an intramolecular homolytic aromatic substitution to rapidly assemble valuable azepinoindolones.