Palladium(II)-Catalyzed Coupling of p-Xylene via Regioselective C−H Activation in TFA

A homocoupling of p-xylene to afford biaryl- or diarylmethane as a major product has been carried out in a catalytic system of Pd(OAc)₂/CF₃CO₂H (TFA)/K₂S₂O₈. In this coupling reaction, the aryl and benzylic C−H bonds of p-xylene can be selectively activated just by tuning the concentration of TFA.