Ru‐NHC‐Catalyzed Asymmetric Hydrogenation of 2‐Quinolones to Chiral 3,4‐Dihydro‐2‐Quinolones

Direct enantioselective hydrogenation of unsaturated compounds to generate chiral three‐dimensional motifs is one of the most straightforward and important approaches in synthetic chemistry. We realized the Ru(II)‐NHC‐catalyzed asymmetric hydrogenation of 2‐quinolones under mild reaction conditions. Alkyl‐, aryl‐ and halogen‐substituted optically active dihydro‐2‐quinolones were obtained in high yields with moderate to excellent enantioselectivities. The reaction provides an efficient and atom‐economic pathway to construct simple chiral 3,4‐dihydro‐2‐quinolones. The desired products could be further reduced to tetrahydroquinolines and octahydroquinolones.