Transition-Metal-Free Access to 2-Subsituted Indolines from Indoles via Dearomative Nucleophilic Addition Using Two-Molecule Organic Photoredox Catalysts

A Photoinduced dearomative nucleophilic addition to N-Boc indoles mediated by two-molecule organic photoredox catalysts such as phenanthrene and 1,4-dicyanobenzene with UV irradiation furnished 2-substituted indolines in moderate quantitative yields. Hydroxide, alkoxide, cyanide ions can be used a nucleophile provide 2-hydroxy, 2-alkoxy, 2-cyanoindolines, respectively. Both electron-rich -deficient indoles, including tryptophan derivatives, employed the photoreaction various indolines. This method provides transition-metal-free access 2-subsituted from using under mild conditions.