Asymmetric transfer hydrogenation of ketones catalyzed by thermoregulated ionic liquid-regulating ruthenium complexes

A sulfonated chiral diamine ligand anion-based functionalized ionic liquid has been synthesized. Then the new ionic liquid-regulating ruthenium complexes were prepared successfully and employed as efficient catalysts for the asymmetric transfer hydrogenation of various ketones. The catalysts were highly efficient for the hydrogenation of a wide range of substrates bearing different functional groups and could be separated easily from the reaction mixture by thermoregulated phase separation, which can be efficiently recycled five times without significant changes in catalytic activity and enantioselectivity.