Hybrid bidentate phosphorus ligands in asymmetric catalysis: Privileged ligand approach vs. combinatorial strategies

In this perspective the development of chiral phosphorus ligands for asymmetric catalysis is discussed, with a special focus on hybrid bidentate phosphorus ligands, in particular phosphine-phosphoramidites. An attempt is made to compare privileged ligand and combinatorial approaches to ligand development - for which the class of phosphine-phosphoramidite ligands is well suited - highlighting differences, similarities and their complementary use.