Role of the base and endogenous anions in "ligand-free" catalytic systems for the Suzuki-Miyaura reaction

UV spectroscopic studies combined with kinetic measurements for the Suzuki-Miyaura reaction catalyzed by "ligand-free" catalytic systems have demonstrated that the base is involved in the formation of the palladium complexes ensuring the occurrence of the transmetalation stage. It follows from UV monitoring data for the catalytic reaction involving aryl iodides that a considerable part of palladium during the process is in the form of Pd2+ acid complexes with endogenous anions and does not participate in the main catalytic cycle.