Self‐Assembly of a Chiral Bis‐phosphine Ligand Bearing Pyridyl Crown Ethers and Chiral Primary Ammoniums: Application to Catalytic Asymmetric Hydrogenation Reactions

A bis-phosphine ligand bearing pyridyl crown ethers was applied to the asymmetric hydrogenation of α-dehydroamino acid esters and quinoxaline derivatives, in which the presence of primary ammonium salts as guests could significantly improve the enantioselectivities.