HARC as an open-shell strategy to bypass oxidative addition in Ullmann–Goldberg couplings

Significance

Copper-catalyzed carbon–nitrogen bond formation has the potential to provide efficient synthetic access to medicinally relevant organic molecules, but broad use of the coupling has been hampered by the requirement for an energetically challenging substrate activation step (oxidative addition into an aryl halide). Here we report a mechanistic alternative that circumvents oxidative addition by cooperatively employing photochemically generated silicon-centered radicals and copper to activate aryl halides via a one-electron pathway. This dramatically increases the range of accessible products, thereby allowing room-temperature synthesis of a diverse electronic and steric range of products traditionally considered inaccessible via copper catalysis due to the prohibitively high barrier for direct copper oxidative addition.