Electron-Deficient Phosphines Accelerate the Heck Reaction of Electronrich Olefins in Ionic Liquid

Using various substrates and ligands, we show that electron-deficient, bidentate phosphines are the ligands of choice for palladium-catalyzed arylation of electron-rich olefins. This is in contrast to the reaction of electron-deficient olefins, which benefit from electron-rich monodentate phosphines. A tentative explanation is offered based on DFT calculations.