Asymmetric Ruthenium-Catalyzed Hydrogenation of Terpyridine-Type N-Heteroarenes: Direct Access to Chiral Tridentate Nitrogen Ligands.

The first enantioselective hydrogenation of terpyridine-type N-heteroarenes has been successfully developed by using Ru(diamine) complexes as catalysts, providing partially reduced chiral pyridine-amine-type products in high yield (up to 93%) with excellent diastereo- and enantioselectivity (up to 94:6 dl/meso, > 99% ee). These pyridine-amine-type compounds can be served as a new class of chiral multidentate nitrogen-donor ligands, which were successfully applied to the Cu-catalyzed asymmetric Friedel-Crafts alkylation reaction of indoles with nitroalkenes.