Visible-Light-Promoted Trifluoromethylation/Ring-Opening Reaction of Vinylcyclopropanes by an EDA Complex

A novel, efficient, and photocatalyst-free method for the 1,5-hydrotrifluoromethylation of vinylcyclopropanes is developed. This transformation is achieved via photoactivation of an electron donor–acceptor (EDA) complex formed between CF 3 Br and TMEDA. The key selectivity challenge is overcome through a hydrogen atom transfer (HAT) mechanism, which redirects the reaction pathway away from conventional halogen-atom transfer (XAT). This practical, metal-free system exhibits a broad substrate scope and high stereoselectivity. The synthetic utility is further demonstrated through product derivatization, and the proposed mechanism is supported by control experiments and DFT calculations.