Asymmetric Hydrogenation of Bis(quinolin-2-yl)methanes: A Direct Access to Chiral 1,3-Diamines

The asymmetric hydrogenation of bis(quinolin-2-yl)methanes was described, using chiral cationic ruthenium/monosulfonated diamine complexes to afford chiral bis(tetrahydroquinolin-2-yl)methanes in high yield with excellent enantioselectivity and diastereoselectivity. The subsequent transformation of these 1,3-diamines to a new class of chiral 6-membered N-heterocyclic carbenes was also developed, which is important but difficult to access.