Optically active a-hydroxy phosphonic acid derivatives are widely used as enzyme inhibitors, antibacterial agents, antiviral agents, antibiotics, anticancer agents, and pesticides, as well as useful building blocks for the synthesis of many other important a-functionalized optically active phosphonates. Therefore, an enantioselective synthesis of these compounds is highly desirable. Asymmetric catalysis has provided several novel solutions for the synthesis of chiral a-hydroxy phosphonic acid derivatives, including asymmetric reduction of ketophosphonates and phosphonylation of carbonyl compounds. For its inherent efficiency and atom economy, much effort in the past few years has been directed toward the development of an asymmetric hydrogenation of a-enol esters of phosphonate substrates. By this means, b-alkyl-substituted a-acyloxy phosphonates were hydrogenated with good enantioselectivities by using Rh catalysts bearing DuPHOS (1,2bis((2R,5R)-2,5-dialkylphospholano)benzene), BisP* ((S,S)1,2-bis(alkylmethylphosphino)ethane), MiniPHOS (R,Rbis(alkylmethylphosphino)methane),and phosphine–phosphite ligands. However, catalyst performance for b-aryland b-alkoxy-substituted substrates was less than satisfactory, as moderate enantioselectivities or low conversions were observed in most cases. Recently, Pizzano and co-workers reported that the use of a phosphine–phosphite/Rh catalyst could give rise to an ee value of up to 92% in the asymmetric hydrogenation of baryl-substituted substrates, although only the b-phenyl-substituted substrate afforded an ee value over 90% under full conversion. As for the hydrogenation of b-alkoxy-substituted substrates, there is only one report on the asymmetric hydrogenation of this class of substrates, in which 87% ee was obtained. Therefore, the highly enantioselective synthesis of a-hydroxy phosphonate derivatives by asymmetric hydrogenation of a-enol ester phosphonates, especially those bearing b-aryl or b-alkoxy substituents, is still a significant challenge for organic chemists. Herein, we report a new chiral phosphine–phosphoramidite ligand derived from (Rc)-1,2,3,4tetrahydro-1-naphthylamine (Rc= central chirality), which promoted unprecedented enantioselectivities (up to 99.9% ee) in Rh-catalyzed asymmetric hydrogenation across a broad range of substrates bearing b-aryl, b-alkoxy, and balkyl substituents. Ligand design has played a pivotal role in the development of efficient metal-catalyzed asymmetric reactions. Although a large number of bidentate phosphorus ligands with C2 symmetry or two closely related binding sites have been prepared and examined for asymmetric hydrogenation, significantly fewer unsymmetrical hybrid bidentate phosphorus ligands were disclosed. We and others have recently revealed that chiral phosphine–phosphoramidite ligands are highly efficient for the asymmetric hydrogenation of various functionalized olefins, including aand b-dehydroamino acid esters, itaconate, and enamides. In our ongoing efforts toward the development of new and practical chiral ligands for use in the hydrogenation of challenging substrates, we designed a class of rigid chiral phosphine–phosphoramidite ligands with a 1,2,3,4-tetrahydronaphthalene backbone. The phosphine–phosphoramidite ligands 1 can be readily prepared from optically pure (Rc)-1,2,3,4-tetrahydro-1-naphthylamine ((Rc)-2) through a concise synthetic procedure (Scheme 1). The initial step involves functionalization of