Asymmetric transfer hydrogenation of beta,gamma-alkynyl alpha-imino esters by a Brønsted acid.

Asymmetric synthesis of trans-alkenyl alpha-amino esters was realized by chiral phosphoric acid catalyzed transfer hydrogenation of beta,gamma-alkynyl alpha-imino esters. Utilizing Hantzsch esters as the hydrogen donor, both the alkyne and imine moieties of beta,gamma-alkynyl alpha-imino esters were reduced to afford trans-alkenyl alpha-amino esters with up to 96% ee.