Enantioselective Synthesis of beta-Aminotetralins via Chiral Phosphoric Acid-catalyzed Reductive Amination of beta-Tetralones

A new protocol for the synthesis of chiral beta-aminotetralins has been developed via chiral phosphoric acid-catalyzed asymmetric reductive amination of beta-tetralones using a Hantzsch ester as an organic hydride donor. Various chiral beta-aminotetralins were obtained in good yields with good to high enantioselectivities. Furthermore, the utility of our new protocol was successfully demonstrated in the enantioselective synthesis of rotigotine.