Chelating Retardation Effect in Nickel Assisted Phosphination: Syntheses of Atropisomeric P,N Ligands

Ni(PPh3)2Cl2 was found to be an effective reagent in nickel assisted phosphination of biaryl O,N triflates with chlorodiphenylphosphine to yield atropisomeric P,N ligands. The chelating effect of the substrates in the reaction played an important role. Only the monodentate PPh3 rather than bidentate dppe (1,2-bis(diphenylphosphino)ethane) nickel complex was found to be an effective reagent.