PipPhos and MorfPhos: Privileged monodentate phosphoramidite ligands for rhodium-catalyzed asymmetric hydrogenation

A library of 20 monodentate phosphoramidite ligands has been prepared and applied in rhodium-catalyzed asymmetric hydrogenation. This resulted in the identification of two ligands, PipPhos and MorfPhos, that afford excellent and in several cases unprecedented enantioselectivities in the hydrogenation of N-acyldehydroamino acid esters, dimethyl itaconate, acyclic N-acylenamides, and cyclic N-acylenamides. In addition, a method for the parallel enantioselectivity determination of eight acylated amines is presented.