Ligand-Promoted Direct C–H Arylation of Simple Arenes: Evidence for a Cooperative Bimetallic Mechanism

A highly
efficient catalyst for the direct C–H arylation
of simple arenes was developed on the basis of a palladium–diimine
complex. The developed catalyst exhibited the highest turnover number
reported to date for the direct arylation of benzene due to increased
stability provided by the diimine ligand. The reaction was also performed
using only 2–3 equiv of simple arenes. Mechanistic studies
in combination with kinetic measurements, isotope effect experiments,
synthesis of possible intermediates, and stoichiometric reactions
suggested that this reaction follows a cooperative bimetallic mechanism.