Unsymmetrical Ferrocenylethylamine-Derived Monophosphoramidites:  Highly Efficient Chiral Ligands for Rh-Catalyzed Enantioselective Hydrogenation of Enamides and α-Dehydroamino Acid Derivatives

A new family of unsymmetrical ferrocenylethylamine-derived monophosphoramidites were synthesized and successfully applied in the Rh-catalyzed enantioselective hydrogenation of a range of enamides and α-dehydroamino acid esters, and ee values of up to 99.5% were obtained for both types of substrate. These results suggest that unsymmetrical amine-derived monophosphoramidites can also exhibit excellent enantioselectivity for a broad range of substrates, comparable to or higher than those of the most efficient symmetrical amine-derived monophosphoramidites reported thus far.