Visible-Light-Mediated Tandem Difluoromethylation/Cyclization of Alkenyl Aldehydes toward CF 2 H-Substituted Chroman-4-one Derivatives.

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