Tandem Radical Cyclization for the Construction of Difluoro-Containing Oxindoles and Quinoline-2,4-diones.

Cu-catalyzed direct difluoromethylation of activated alkenes through a difluoromethyl radical addition/cyclization to afford difluorinated oxindoles and quinoline-2,4-diones has been developed. This method provides convenient access to a variety of oxindoles and quinoline-2,4-diones under mild conditions via a proposed tandem radical cyclization process, while tolerating various functional groups well. Moreover, a facile method to construct diverse difluorinated quinoline-2,4-diones by visible-light photoredox catalysis under mild conditions was presented.