Highly Enantioselective Synthesis of Chiral Benzhydrols via Manganese Catalyzed Asymmetric Hydrogenation of Unsymmetrical Benzophenones Using an Imidazole-Based Chiral PNN Tridentate Ligand.

A series of Mn(I) catalysts containing imidazole-based chiral PNN tridentate ligands with controllable "side arm" groups have been established, enabling the asymmetrical hydrogenation of unsymmetrical benzophenones with outstanding activity (up to 13 000 TON) and excellent enantioselectivity (up to >99% ee). This protocol uses KCO as an industrially desirable base and features a wide substrate scope and functional group tolerance. Moreover, the imine group in the catalyst is crucial for accessing high activities and good enantioselectivities.

The cinchona alkaloid squaramide catalyzed asymmetric Pictet-Spengler reaction and related theoretical studies.

The asymmetric Pictet-Spengler reaction between tryptamine derivatives and aldehydes has been developed with a cinchona alkaloid squaramide as the catalyst, affording the corresponding tetrahedron-β-carbolines in good to excellent yields and ee values. A rational mechanistic pathway has also been proposed based on DFT calculations.