Novel recoverable catalysts for asymmetric transfer hydrogenation

9-Amino(9-deoxy)epiquinine and 9-amino(9-deoxy)epicinchonine were applied in asymmetric transfer hydrogenation of aromatic ketones in both iridium and rhodium catalytic systems using i-propanol as the hydrogen source. Good to excellent conversions and enantioselectivities were observed with a variety of aromatic ketones. Moreover, the Ir complex and Rh complex of 9-amino(9-deoxy)cinchonine were recovered in high yields with dilute hydrochloric acid. The enantioselectivity of 1-phenylethanol was nearly maintained after six cycles.

9-Amino(9-deoxy)epiquinine and 9-amino(9-deoxy)epicinchonine were successfully applied in asymmetric transfer hydrogenation in both iridium and rhodium catalytic systems. Moreover, the Ir complex and Rh complex of 9-amino(9-deoxy)epicinchonine were recovered in high yields with dilute hydrochloric acid.