Negishi Coupling of Secondary Alkylzinc Halides with Aryl Bromides and Chlorides

An efficient palladium-catalyzed process has been developed for Negishi coupling of secondary alkylzinc halides with a wide range of aryl bromides and activated aryl chlorides. A palladium catalyst composed of a new biaryidialkylphosphine ligand, CPhos, effectively promotes the rate of the reductive elimination step relative to the rate of the undesired B-hydride elimination. The broad substrate scope and excellent ratio of the desired secondary to the undesired primary coupling product make this method a powerful and reliable tool for C(sp(3))-C(sp(2)) bond formation.