Cobalt-Catalyzed Diastereoselective Difluoroalkylation/Giese Addition Domino Reactions.

An efficient cobalt-catalyzed difluoroalkylation/Giese radical conjugate cyclization manifold with various alkyne-tethered cyclohexadienones and halogenated fluorinating reagents was accomplished under remarkable mild reaction conditions, thus providing an expedient route to valuable fluorinated chromens. The utility of this transformation was demonstrated by high site selectivity as well as chemo- and diastereoselectivity, broad substrate scope, excellent functional group tolerance, and facile late-stage modification.