Unsymmetrical hybrid ferrocene-based phosphine-phosphoramidites: a new class of practical ligands for Rh-catalyzed asymmetric hydrogenation.
[reaction: see text] The synthesis and application of a new family of air-stable, highly unsymmetrical ferrocene-based phosphine-phosphoramidites is described. The new ligands exhibit excellent enantioselectivities (over 99% ee) in the Rh-catalyzed asymmetric hydrogenation of enamides, dimethyl itaconate, and methyl (Z)-acetamidocinnamate even with high catalyst turnovers (S/C=10,000). The binaphthyl moiety is crucial for reactivity and enantioselectivity, and its absolute configuration plays a dominant role in determining the chirality of the hydrogenation products.
Hu
Xiang-Ping
XP
Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China.
Zheng
Zhuo
Z