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

An efficient CuI-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.