Ligand-Determined Single, Double, and Triple C–H Arylation of Aryl Phosphines at Will

Controllable ortho-C–H arylation of aryl phosphines would provide a foundation for the modular synthesis of electronically and sterically tunable biaryl phosphines. However, this central task is challenging owing to the unfavorable four-membered cyclometalation and high tendency to undergo further interannular arylation. Herein phenolic compounds have been found to be effective ligands to determine single, double, or triple C–H arylation at will, providing a streamlined and practical synthetic approach to access (diaryl)- and (dialkyl)-biarylphosphines. The phosphine ligand library has been proven to be effective in catalytic coupling reactions and even exhibits unique chemoselectivity in comparison with commercially available classic phosphine ligands.