Asymmetric Preparation of anti-β-Hydroxyα-amino Acid Esters

Significance

A cationic Ir(I) complex was used to effect the anti-selective hydrogenation of α-amino-β-keto esters via dynamic kinetic resolution (DKR) under mild conditions. The authors reported on new conditions for their previously developed system for the same reaction (K. Makino, Y. Hiroki, Y. Hamada J. Am. Chem. Soc. 2005, 127, 5784-5785). Now, using a cationic Ir(I) catalyst, yields were increased by ˜20% for all tested substrates and enantioselectivity was slightly increased in some cases. Another advantage is that the cationic catalyst allowed hydrogenation under 4.5 atm H₂ instead of the previously reported 100 atm.