A series of small bite-angle phosphine-phosphite (P-OP) ligands have been synthesized by a two-step method. The key intermediate was prepared by an unprecedented asymmetric carbonyl reduction of a phosphamide using the CBS (Corey-Bakshi-Shibata) catalyst. The topology of these ligands (a configurationally stable stereogenic carbon with two heteroatom substituents) and their small bite-angle (created by the close proximity of the two ligating groups to the metal center) together provide a rigid asymmetric environment around this center, enabling high stereoselectivity in hydroformylations and hydrogenations of standard substrates.
![Small Bite-Angle P-OP Ligands for Asymmetric Hydroformylation and Hydrogenation](https://www.iciq.org/wp-content/uploads/2014/03/Small-Bite-Angle-P-OP-Ligands_ol-2013-01494x_0010.gif)