Asymmetric Transfer Hydrogenation of β,γ-Alkynyl α-Imino Esters by a Brønsted Acid

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