Photocatalytic C-F bond activation in small molecules and polyfluoroalkyl substances

Organic halides are highly useful compounds in chemical synthesis, in which the halide serves as a versatile functional group for elimination, substitution and cross-coupling reactions with transition metals or photocatalysis^1-3. However, the activation of carbon-fluorine (C-F) bonds-the most commercially abundant organohalide and found in polyfluoroalkyl substances (PFAS), or 'forever chemicals'-is much rarer. Current approaches based on photoredox chemistry for the activation of small-molecule C-F bonds are limited by the substrates and transition metal catalysts needed⁴. A general method for the direct activation of organofluorines would have considerable value in organic and environmental chemistry. Here we report an organic photoredox catalyst system that can efficiently reduce C-F bonds to generate carbon-centred radicals, which can then be intercepted for hydrodefluorination (swapping F for H) and cross-coupling reactions. This system enables the general use of organofluorines as synthons under mild reaction conditions. We extend this method to the defluorination of PFAS and fluorinated polymers, a critical challenge in the breakdown of persistent and environmentally damaging forever chemicals.