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.