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 biaryldialkylphosphine ligand, CPhos, effectively promotes the rate of the reductive elimination step relative to the rate of the undesired beta-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.