Copper-mediated etherification via aryl radicals generated from triplet states

Abstract Carbon–heteroatom (C–X) cross-coupling is a common method for bond-forming reactions in chemistry but the more electronegative heteroatom X is, challenging bond formation becomes. Although reductive elimination from Cu(III) intermediates to form C–X bonds generally facile reaction, oxidative addition of Cu(I) into carbon–(pseudo)halide aryl (pseudo)halides energetically challenging. Therefore, halides with variety nucleophiles currently out reach methods based on copper. Here we present strategy bypass high-barrier step by generation radicals triplet states. Photoinduced energy transfer to, or direct excitation of, even enables use chlorides as electrophilic coupling partners. This allows alcohols, amines and fluoride expands scope copper-mediated chemistry.