Photocatalytic Synthesis of Indoles via NHC‐Boryl Radical Cascade Cyclization of 2‐Vinylaryl Isocyanides

A thiol/photoredox dual catalytic protocol has been developed for the synthesis of C2‐borylated indoles from 2‐vinylaryl isocyanides and NHC‐boranes. Under visible‐light irradiation, NHC‐boryl radicals are generated in situ and undergo addition to the isocyanide unit, followed by intramolecular cyclization to deliver the indole framework. The method proceeds under mild conditions, exhibits good functional‐group tolerance, and affords the products with high regioselectivity. Gram‐scale experiments and the synthesis of tri ‐indolyl NHC‐borane further demonstrate the synthetic utility of this protocol.