Cinchona-Alkaloid-Derived NNP Ligand for Iridium-Catalyzed Asymmetric Hydrogenation of ß-Keto Ester.

The Ir-catalyzed asymmetric hydrogenation of ß-keto esters with Cinchona-alkaloid-derived NNP ligands has been developed. ß-Hydroxy esters of opposite configuration were afforded smoothly with 91.5-99.1 and 81.6-99.3% ee, respectively, using NNP L2 and L7 derived from quinidine and quinine separately even on the gram scale. The protocol for the preparation of ß-hydroxy esters of opposite configuration by the simple conversion of ligand configurations offered further opportunities for the synthesis of biologically active molecules and drugs.