Manganese-Catalyzed Asymmetric Hydrogenation of Quinolines Enabled by a Dual “N–H Effect”

The first example of non-noble metal-catalyzed asymmetric hydrogenation of aromatic N-heterocycles is reported. A new chiral pincer manganese catalyst showed outstanding catalytic activity in the asymmetric hydrogenation of a wide range of quinolines, affording high yields and excellent enantioselectivities (up to 97% ee). A turnover number of 3840 was reached at a low catalyst loading (S/C=4000), which was competitive with the activity of most effective noble metal catalysts for this reaction. The high reactivity of the manganese catalyst and a precise regulation of the enantioselectivity were ensured by a dual “N–H” effect of the ligand structure.