Generation of the SCF₃ Radical by Photoredox Catalysis: Intra- and Intermolecular Carbotrifluoromethylthiolation of Alkenes

We report the first use of N-trifluoromethylthiosaccharin as the source of SCF₃ radical under photoredox catalysis. This allowed an efficient and general visible-light-mediated carbotrifluoromethylthiolation of alkenes. Under the optimized conditions using fac-[Ir(ppy)₃ ] as the photocatalyst, various N-aryl acrylamides as well as a wide range of substituted styrenes can readily be difunctionalized in an intra- or intermolecular fashion, affording the corresponding SCF₃ -containing products in good to excellent yield. Importantly, the formation of this SCF₃ radical along with other key radical intermediates was unambiguously demonstrated thanks to spin trapping/electron paramagnetic resonance (ST/EPR) experiments, which enabled a clear understanding of the reaction mechanism.