Click-connected ligand scaffolds: Macrocyclic chelates for asymmetric hydrogenation

Click chemistry is used to construct ligand scaffolds for a series of chiral diphosphites. Enantioselectivity as high as 97% ee is obtained using these click ligands in rhodium-catalyzed asymmetric hydrogenation. Control experiments and spectroscopic data suggest that a 16-membered PP-macrocyclic Rh(I) chelate is formed.