Phototriggered Fluoroalkylation/Cyclization of Unactivated 1-Acryloyl-2-cyanoindoles: Synthesis of RCOCF2-Substituted Pyrrolo[1,2-a]indolediones.

A photochemical approach toward RCOCF2-substituted pyrrolo[1,2-a]indolediones was developed by the radical cascade difluoroalkylation/cyclization reaction of unactivated 1-acryloyl-2-cyanoindoles with ethyl iododifluoroacetate or iododifluoramides under visible-light irradiation. This transition-metal- and photosensitizer-free protocol afforded diverse difluoroalkylated pyrrolo[1,2-a]indolediones in moderate to good yields under mild reaction conditions. Most appealingly, the reaction can proceed smoothly under sunlight irradiation, which opens a new avenue toward difluoroalkylated pyrrolo[1,2-a]indolediones.