Xihong Liu

Construction of Vicinal Tetrasubstituted Stereocenters with a C-F Bond through a Catalytic Enantioselective Detrifluoroacetylative Mannich Reaction

An efficient asymmetric detrifluoroacetylative Mannich reaction of 2-fluoro-1,3-diketones/hydrates with isatin-derived ketimines catalyzed by a chiral copper(II)-diamine complex has been realized. The reaction afforded a series of 3-substituted 3-amino-2-oxindoles bearing fluorine-containing vicinal tetrasubstituted stereocenters in high yields (up to 99%) with excellent diastereoselectivities (up to >20:1 dr) and enantioselectivities (up to 94% ee).

Catalytic Asymmetric Inverse-Electron-Demand 1,3-Dipolar Cycloaddition of C,N-Cyclic Azomethine Imines with Azlactones: Access to Chiral Tricyclic Tetrahydroisoquinolines.

Reported herein is a bifunctional-organocatalyst-mediated enantioselective inverse-electron-demand 1,3-dipolar cycloaddition of C,N-cyclic azomethine imines with azlactones. The strategy provides concise access to enantioenriched C1-substituted tetrahydroisoquinolines featuring a pyrazolidinone scaffold. Moreover, the scalability and practical utility of this protocol was well demonstrated by employing a gram-scale reaction and some representative transformations.

MgII-Catalyzed Desymmetrization Reaction of meso-Aziridines with Hydroxylamines: Synthesis of Novel Chiral 1,2-Diamine Skeletons

A MgII -catalyzed desymmetrization reaction of meso-aziridines with hydroxylamines has been disclosed for the first time. A series of novel chiral 1,2-diamine skeletons were obtained in good yields and enantioselectivities. The reaction employed magnesium catalysis generated in situ from a simple oxazoline-OH chiral ligand. Obviously, the diverse structures of the obtained chiral 1,2-diamine compounds could allow them to be potential chiral ligands in future catalytic asymmetric synthesis studies.

An Efficient Nickel-Catalyzed Asymmetric Oxazole-Forming Ugi-Type Reaction for the Synthesis of Chiral Aryl-Substituted THIQ Rings

A nickel-catalyzed asymmetric oxazole-forming Ugi reaction of C,N-cyclic azomethine imines and isonitriles is disclosed. The reported protocol proceeds smoothly, and gives the corresponding adducts, which contain two important pharmaceutically active ring-systems (tetrahydroquinoline and oxazole rings), in good yields and excellent enantioselectivities by employing an easily accessible chiral diamine as a ligand. This simple and efficient strategy provides easy access to a series of C1-substituted aryl tetrahydroisoquinolines.

The Important Role of the Byproduct Triphenylphosphine Oxide in the Magnesium(II)‐Catalyzed Enantioselective Reaction of Hemiacetals and Phosphorus Ylides

By employing a simple in situ generated magnesium catalyst, a direct asymmetric reaction between hemiacetals and phosphorus ylides was achieved through a tandem Wittig-oxa-Michael reaction sequence. Enantioenriched chromans, isochromans, and tetrahydropyrans were obtained in good chemical yields, and (-)-erythrococcamide B was synthesized in enantioenriched form. The byproduct triphenylphosphine oxide was identified as a necessary additive for this process.