Copper-Catalyzed Suzuki-Miyaura Coupling of Arylboronate Esters: Transmetalation with (PN)CuF and Identification of Intermediates

An efficient Cu-I-catalyzed Suzuki-Miyaura reaction was developed for the coupling of aryl- and heteroarylboronate esters with aryl and heteroaryl iodides at low catalyst loadings (2 mol %). The reaction proceeds under ligand-free conditions for aryl heteroaryl and heteroaryl heteroaryl couplings. We also conducted the first detailed mechanistic studies by synthesizing [(PN-2)CuI](2), [(PN-2)CuF](2), and (PN-2)CuPh (PN-2 = o-(di-tert-butylphosphino)-N,N-dimethylaniline) and demonstrated that [(PN-2)CuF](2) is the species that undergoes transmetalation with arylboronate esters.