Photocatalytic Synthesis of Polycyclic Indolones

In this work, a photocatalytic strategy for a rapid and modular access to polycyclic indolones starting from readily available indoles is reported. 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, it was 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.