Rh‐Catalyzed Enantioselective Hydrogenation of N ‐Aryl α ‐Aminofumaric Acid Derivatives for Synthesis of Chiral Aspartates

Rh‐catalyzed asymmetric hydrogenation of α‐ aminofumaric acid derivatives including α ‐aminofumaric acid diesters and unsaturated 1,4‐benzoheterocycle esters has been successfully achieved. By this method, a variety of chiral N ‐substituted aspartic acid diesters, 2‐(2‐oxo‐3,4‐dihydro‐2 H ‐benzo[ b ][1,4]oxazin‐3‐yl)acetates, and 2‐(3‐oxo‐1,2,3,4‐tetrahydroquinoxalin‐2‐yl)acetates can be prepared in high yields (94%–99%) with excellent enantioselectivities of up to 99% ee and high turnover numbers (TON up to 1000) achieved. Significantly, this strategy provides an efficient and high enantioselective approach to synthesis of chiral free secondary amines.