text: Chiral phosphine ligands, especially C-symmetric ligands, are the source of chirality in most asymmetric hydrogenation catalysts. Of these the BINAP ligand is well-known, as a result of its Nobel Prize-winning application in the Noyori asymmetric hydrogenation.
  Chiral phosphine ligands can be generally classified as mono- or bidentate.  They can be further classified according to the location of the stereogenic centre – phosphorus vs the organic substituents.  Ligands with a C symmetry element have been particularly popular, in part because the presence of such an element reduces the possible binding conformations of a substrate to a metal-ligand complex dramatically (often resulting in exceptional enantioselectivity).