Palladium‐Catalyzed Arylation Reactions: A Mechanistic Perspective

After being restricted for the intramolecular formation of C–C bonds, the palladium catalyzed arylation reaction has been extended for the intermolecular synthesis of biaryls systems. Many of these reactions have been demonstrated to proceed by mechanisms that involve a concerted metalation–deprotonation, in which the base plays an important role in the proton abstraction. Other mechanisms based on electrophilic aromatic substitution and on Pd II /Pd IV or Pd II /Pd III catalytic cycles have also been proposed. This review summarizes the most important recent advancements on the mechanistic understanding of the different types of palladium‐catalyzed arylations reactions.