Rh-Catalyzed Asymmetric Hydrogenation of (Z)-β-Phosphorylated Enamides: Highly Enantioselective Access to β-Arninophosphines

A catalytic asymmetric hydrogenation of beta-phosphorylated enamides for enantioselective access to optically active beta-aminophosphine derivatives is reported. Critical to the success of this method was the employment of rhodium catalysis in concert with an unsymmetrical hybrid chiral phosphine-phosphoramidite ligand. A wide range of aromatic beta-phosphorylated enamides could be hydrogenated in full conversion and with perfect enantioselectivity even at low catalyst loadings (S/C = 1000). beta-Aminophosphine oxides could be readily hydrolyzed and reduced, thus providing an efficient route to catalytically important chiral beta-aminophosphines.