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 biaryldialkylphosphine ligand, CPhos, effectively promotes the rate of the reductive elimination step relative to the rate of the undesired β-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(sp3)−C(sp2) bond formation.
“Negishi Coupling of Secondary Alkylzinc Halides with Aryl Bromides and Chlorides”, J. Am. Chem. Soc., 2009, 131, 7532-7533.