Highly stereoselective synthesis and application of P-chiral ferrocenyl bisphosphorus ligands for asymmetric hydrogenation

New, efficient and highly stereoselective methods were developed for the synthesis/modification of Wudaphos type ligands. It was found that the "three hindered quadrant" model is crucial to ensure high enantiomeric control and that the substituents on the phosphine atom should be electron rich to increase the reactivity. Moreover, a new SPO-Wudaphos ligand was developed, which exhibited good to excellent enantioselectivities in the asymmetric hydrogenation of alpha-methylene-gamma-keto carboxylic acids.