Visible-Light-Mediated Tandem Difluoromethylation/Cyclization of Alkenyl Aldehydes toward CFH-Substituted Chroman-4-one Derivatives.

An efficient and facile visible-light-mediated tandem difluoromethylation/cyclization of alkenyl aldehydes, with easily accessible and air-stable [PhPCFH]Br as the difluoromethylation reagent, has been established. A range of CFH-substituted chroman-4-one skeletons and their derivatives, such as 2,3-dihydroquinolin-4(1)-ones, chroman, 3,4-dihydronaphthalen-1(2)-one, 2,3-dihydrobenzofuran, and 2,3-dihydro-1-inden-1-one, are efficiently produced in moderate to good yields with excellent chemoselectivity under mild reaction conditions.