New Horizons of Photocatalytic Fluoromethylative Difunctionalization of Alkenes

Summary Radical tri- and difluoromethylation (fluoromethylation) by photoredox catalysis has emerged as a new synthetic methodology over the past several years. In particular, the strategy is useful for the introduction of a fluoromethyl group (CF 2 X, X = F or H) and a different functional group across a carbon-carbon double bond via a single operation. Step-economical synthesis of diverse organofluorine compounds bearing a C(sp 3 )–CF 2 X bond has been achieved. In this review, the discussion focuses on recent representative examples of photoredox-catalyzed fluoromethylative difunctionalization of alkenes through redox-neutral processes. Close attention is paid to the choice of the fluoromethylating reagent and the photocatalyst. The basic concept, reaction design, and the prospects for this research area are also discussed.