Visible-light Photoredox-Catalyzed Radical Aryldifluoromethylation of N-arylacrylamides with S-(difluoromethyl)sulfonium Salt.

A facile and highly efficient visible-light photoredox-catalyzed protocol for aryldifluoromethylation of acrylamides was developed using S-(difluoromethyl)sulfonium salt as the difluoromethyl source. With this method, pharmaceutically interesting CF2H-containing oxindoles were readily accessed from N-arylacrylamides, and this method featured mild reaction conditions, a broad scope of substrates, good tolerance of functional groups, and good to excellent yields. Control experiments revealed that this protocol proceeded through a difluoromethylation/cyclization cascade process.