Metal‐Free Catalytic Hydrogenation

Phosphonium borates of the form R2PH(C6F4)BH(C6F5)2 are shown to be metal-free hydrogenation catalysts (see scheme) that effect reduction of sterically hindered imines and aziridines, as well as B(C6F5)3-protected unhindered imines and nitriles, at relatively low H2 pressures and temperatures.