Study On Asymmetric Catalysis Of β-CF 3 -α, β-unsaturated Ketone And α-trifluoromethylimine By Chiral Ruthenium Catalyst

Chiral alcohols and chiral amines are common organic compounds, which widely exists in nature. They have important applications in pesticides, pharmaceuticals, fine chemicals and other fields. How to efficiently get chiral alcohols and amines are hot research in recent decades. Many catalysts and methods have been developed. Asymmetry reduction of the corresponding prochiral ketones, imines(metal-hydrogen reduction, hydrogenation, transfer hydrogenation) is an effective way to obtain these types of chiral compounds. Compared to hydrogenation, other cheaper hydrogen donor be used instead of hydrogen.So reaction condition of asymmetric hydrogen transfer is mild and the operation is simple. And it is rapidly developing these years.Heterogenous catalysts have not only solved problems of recycling but also overcomed the issues of environmental polution.The great perspective of this kind of catalyst caught many scientists’ eyes. And in the area of multiphase reaction, mesoporous silica materials have always been playing crucial roles.(1): Organoruthenium-functionalized mesoporous silica nanospheres are prepared through the co-assembly of chiral 4-(trimethoxysilyl)ethyl)phenylsulfonyl-1,2-diphenylethylene-diamine and tetraethoxysilane followed by complexation with an organoruthenium complex. Structural analysis and characterization disclose its well-defined single-site organoruthenium active center, and electron microscopy images reveal its uniformly distributive, mesostructured nanospheres. As a heterogenous catalyst, it displays high catalytic activity and enantioselectivity in the asymmetric 1,2-reductions of β-trifluoromethylated-α,β-unsaturated ketones to give chiral allylic alcohols, resulting in up to 97% enantioselectivity with a wide scope of substrates. Furthermore, this heterogeneous catalyst can be conveniently recovered and reused for at least eight times without loss of catalytic activity, showing particularly attractive in the practice of organic synthesis(2): Facile enantioselective transformation of strong electron-withdrawing acyclic α-trifluoromethylimines to α-trifluoromethylamines through a ruthenium-catalyzed asymmetric transfer hydrogenation has been developed. The method described here is environmentally friendly process with sodium formate as a hydrogen source and water-dimethylformamide as a co-solvent. Benefit of this enantioselective transformation affords a series of chiral α-trifluoromethylamines with high yields and excellent enantioselectivities(93-99% ee), as well as tolerance for a wide variety of functional groups under a wild reaction condition.