Potassium ethoxide/phenanthroline promoted chemoselective direct C-H arylation of unactivated arenes with aryl iodides

Simple and cheap potassium ethoxide (EtOK) and a catalytic amount of phenanthroline can efficiently promote the direct C-H arylation of unactivated arenes with aryl iodides at 80 °C. This transition-metal-free base-promoted homolytic aromatic substitution offers a chemoselective approach to synthesize biaryls bearing active halo substituents (I, Br, Cl, etc.) in good yields.