XAT-Catalysis for Intramolecular Biaryl Synthesis.

Radical ipso-substitution offers an alternative to organometallic approaches for biaryl synthesis, but usually requires stoichiometric reagents such as tributyltin hydride. Here, we demonstrate that visible light photoredox catalysis can be used for ipso-biaryl synthesis, via a halogen-atom transfer (XAT) regime. Using amide substrates that promote ipso- over unwanted ortho-addition, we demonstrate smooth biaryl formation with no constraint on the electronic character of the migrating arene ring. The photoreaction can be combined in one operation to achieve a formal arylation of the inert aniline C-N bond.