Molecular Insights into the Ligand‐Reactant Interactions of Pt Nanoparticles Functionalized with α‐Amino Acids as Asymmetric Catalysts for β‐Keto Esters. Issue 11 (3rd May 2019)

• Record Type: Journal Article
• Authors: Šulce, Anda; Mitschke, Nico; Azov, Vladimir; Kunz, Sebastian
• Is Part Of: ChemCatChem. Volume 11:Issue 11(2019)
• Page Start: 2732
• Page End: 2742
• Publication Date: 2019-05-03
• Subjects: Ligand-functionalized nanoparticles -- ligand-reactant interactions -- nonlinear effects -- selectivity control -- stereoselective heterogeneous catalysis; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.201900238
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: The asymmetric hydrogenation of ß‐keto esters over α‐amino acid‐functionalized Pt nanoparticles was explored in order to expand our understanding of ligand‐reactant interactions underlying the chiral induction. A comprehensive investigation aimed at the quantification of the nonlinear effects demonstrated that for most of the ligands and reactants enantiodifferentiation is determined by 1 : 1 ligand‐reactant interaction. However, attachment of phenyl substituents to the ligands or reactants likely involves the formation of more intricate intermediate complexes. We have shown that the asymmetric bias is sensitive to even small changes in the geometry of the ligand. Additionally, we have found that alkali metal cations, which balance the negative charge of the ligand's carboxyl group and originate from the metal hydroxide used for ligand functionalization, play a key role in the process of chiral induction. As the nature of the cation can be varied by simply changing the metal hydroxide used during functionalization, this finding opens an additional possibility to control the stereoselectivity by tuning the ligand‐reactant interaction. Abstract : Understanding of ligand‐reactant interactions : In the asymmetric hydrogenation of ß‐keto esters over α‐amino acid‐functionalized supported Pt nanoparticles the stereoselectivity is mainly determined by a 1 : 1 ligand‐reactant interaction and further influenced by small geometric changes in the ligand structure as well as by the alkali metal cation coordinated to the ligand.