Photocatalytic Activation of Fluoroform for Radical Trifluoromethylation

Fluoroform is an ideal trifluoromethyl source in synthetic chemistry due to its low cost, low toxicity, and high potential for greenhouse-gas valorization. However, the use of fluoroform has been largely limited to the generation of trifluoromethyl anions or metal-bound species; direct access to the trifluoromethyl radical remains elusive, despite its broad applicability for preparing medicinally important trifluoromethylated compounds. Here, we report a method to generate the trifluoromethyl radical in situ from fluoroform via photochemical activation. Leveraging the reactivity of ketones in combination with a Brønsted base under photoirradiation enables the direct use of fluoroform for the radical trifluoromethylation of alkenes and arenes. This approach is amenable to a photocatalytic protocol and enables the conversion of bulk chemicals into a high-value trifluoromethylated compound.