Design and Preparation of a Chiral Ligand Based on a Pseudorotaxane Skeleton: Application to Rhodium-Catalyzed Enantioselective Hydrogenation of Enamides

We have prepared a novel pseudorotaxane molecule which works as a chiral bidentate ligand having a phosphine moiety in an axle and a phosphite moiety in a wheel as two coordination sites and applied it successfully to the rhodium-catalyzed enantioselective hydrogenation of enamides (up to 96% ee). To the best of our knowledge, this is the first successful example of the use of the pseudorotaxane molecule as a chiral ligand for homogeneous transition-metal-catalyzed asymmetric reactions.