<i>C1</i>-Symmetric PNP Ligands for Manganese-Catalyzed Enantioselective Hydrogenation of Ketones: Reaction Scope and Enantioinduction Model
Liyao Zeng, Huaxin Yang, Menglong Zhao, Jialin Wen, James H. R. Tucker, Xumu Zhang
Abstract
A family of ferrocene-based chiral PNP ligands is reported. These tridentate ligands were successfully applied in Mn-catalyzed asymmetric hydrogenation of ketones, giving high enantioselectivities (92%∼99% ee for aryl alkyl ketones) as well as high efficiencies (TON up to 2000). In addition, dialkyl ketones could also be hydrogenated smoothly. Manganese intermediates that might be involved in the catalytic cycle were analyzed. DFT calculation was carried out to help understand the chiral induction model. The Mn/PNP catalyst could discriminate two groups with different steric properties by deformation of the phosphine moiety in the flexible 5-membered ring.
Topics & Concepts
ChemistryCatalysisEnantioselective synthesisMoietySteric effectsAsymmetric inductionAsymmetric hydrogenationPhosphineManganeseCatalytic cycleFerroceneArylAlkylCombinatorial chemistryMedicinal chemistryOrganic chemistryElectrochemistryElectrodePhysical chemistryAsymmetric Hydrogenation and CatalysisSurface Chemistry and CatalysisCatalysis for Biomass Conversion