Highly Enantioselective Synthesis of α‐Hydroxy Phosphonic Acid Derivatives by Rh‐Catalyzed Asymmetric Hydrogenation with Phosphine–Phosphoramidite Ligands

A class act: Unsymmetrical hybrid phosphine–phosphoramidite ligands with central and axial chirality are applied to the highly enantioselective hydrogenation of various enol ester phosphonates (see scheme; cod=cycloocta-1,5-diene). Enantioselectivities up to 99.9 % ee are obtained for all classes of β-aryl, β-alkoxy, and β-alkyl substrates.