Designing New Magnesium Pincer Complexes for Catalytic Hydrogenation of Imines and <i>N</i>‑Heteroarenes: H₂ and N–H Activation by Metal–Ligand Cooperation as Key Steps

Utilization of main-group metals as alternatives to transition metals in homogeneous catalysis has become a hot research area in recent years. However, their application in catalytic hydrogenation is less common due to the difficulty in heterolytic cleavage of the H–H bond. Employing aromatization/de-aromatization metal–ligand cooperation (MLC) highly enhances the H2 activation process, offering an efficient approach for the hydrogenation of unsaturated molecules catalyzed by main-group metals. Herein, we report a series of new magnesium pincer complexes prepared using PNNH-type pincer ligands. The complexes were characterized by NMR and X-ray single-crystal diffraction. Reversible activation of H2 and N–H bonds by MLC employing these pincer complexes was developed. Using the new magnesium complexes, homogeneously catalyzed hydrogenation of aldimines and ketimines was achieved, affording secondary amines in excellent yields. Control experiments and DFT studies reveal that a pathway involving MLC is favorable for the hydrogenation reactions. Moreover, the efficient catalysis was extended to the selective hydrogenation of quinolines and other N-heteroarenes, presenting the first example of hydrogenation of N-heteroarenes homogeneously catalyzed by early main-group metal complexes. This study provides a new strategy for hydrogenation of CN bonds catalyzed by magnesium compounds and enriches the research of main-group metal catalysis

Chiral Selenide-Catalyzed Enantioselective Allylic Reaction and Intermolecular Difunctionalization of Alkenes: Efficient Construction of C‑SCF₃ Stereogenic Molecules

New approaches for the synthesis of enantiopure trifluoro­methyl­thiolated molecules by chiral selenide-catalyzed allylic trifluoro­methyl­thiolation and inter­molecular difunctionalization of unactivated alkenes are disclosed. In these transformations, functional groups were well tolerated, and the desired products were obtained in good yields with excellent chemo-, enantio-, and diastereo­selectivities. This reaction is nicely complementary to enantio­selective trifluoro­methyl­thiolation, allylic functionalization, and inter­molecular alkene difunctionalization

Chiral Selenide-Catalyzed Enantioselective Allylic Reaction and Intermolecular Difunctionalization of Alkenes: Efficient Construction of C‑SCF₃ Stereogenic Molecules

New approaches for the synthesis of enantiopure trifluoro­methyl­thiolated molecules by chiral selenide-catalyzed allylic trifluoro­methyl­thiolation and inter­molecular difunctionalization of unactivated alkenes are disclosed. In these transformations, functional groups were well tolerated, and the desired products were obtained in good yields with excellent chemo-, enantio-, and diastereo­selectivities. This reaction is nicely complementary to enantio­selective trifluoro­methyl­thiolation, allylic functionalization, and inter­molecular alkene difunctionalization

Chiral Selenide-Catalyzed Enantioselective Allylic Reaction and Intermolecular Difunctionalization of Alkenes: Efficient Construction of C‑SCF₃ Stereogenic Molecules

New approaches for the synthesis of enantiopure trifluoro­methyl­thiolated molecules by chiral selenide-catalyzed allylic trifluoro­methyl­thiolation and inter­molecular difunctionalization of unactivated alkenes are disclosed. In these transformations, functional groups were well tolerated, and the desired products were obtained in good yields with excellent chemo-, enantio-, and diastereo­selectivities. This reaction is nicely complementary to enantio­selective trifluoro­methyl­thiolation, allylic functionalization, and inter­molecular alkene difunctionalization