A Powerful Brønsted Acid Catalyst for the Organocatalytic Asymmetric Transfer Hydrogenation of Imines

A little goes a long way: A 1 mol % loading of the chiral phosphoric acid catalyst 2 converts aromatic and aliphatic imines such as 1 into the corresponding amines (4) in high yields and enantioselectivities if treated with Hantzsch dihydropyridine 3.