In this work, we exploit our strategy of secondary-sphere modification of organocatalysts to improve the reactivity and selectivity of amino catalysts. Herein, the carboxylic acid moiety of proline was targeted as a site for modification under catalytic reaction conditions with boronic acids. Intermolecular aldol reactions between aromatic aldehydes and cyclopentanone were selected as a proof-of-concept because cyclopentanone as an aldol donor was often associated with decreased selectivity compared to its 6-membered ring analog, hexanone. Our secondary-sphere modification strategy, using naturally occurring L-proline amino acid, enabled reactions at room temperature with high levels of diastereo- and enantio-selectivity and short reaction times. NMR and HR-MS studies shed light on the nature of the catalyst structure and on the role of water in our reactions.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1039/d1cc05589e | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Tuning Secondary-Sphere Lewis Acidity via Late-Stage Modification of an Appended Borane.
Inorg Chem
December 2024
Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.
To develop synthetic strategies to construct ligands containing secondary-sphere acids, we demonstrate that an appended borane of low Lewis acidity (-BPin) can be upgraded to a strong Lewis acid (-BF). Using a pyridine-pyrazole ligand coordinated to Mo(CO), we show that a pendent -BPin group undergoes exhaustive fluorination to -BFK, a precursor to a highly acidic -BF unit (acceptor number ∼15× greater than that of -BPin).
View Article and Find Full Text PDFExperimentally validating sabatier plot by molecular level microenvironment customization for oxygen electroreduction.
Nat Commun
July 2024
College of Chemistry and Chemical Engineering/Film Energy Chemistry for Jiangxi Provincial Key Laboratory (FEC), Nanchang University, Nanchang, 330031, PR China.
Microenvironmental modifications on metal sites are crucial to tune oxygen reduction catalytic behavior and decrypt intrinsic mechanism, whereas the stochastic properties of traditional pyrolyzed single-atom catalysts induce vague recognition on structure-reactivity relations. Herein, we report a theoretical descriptor relying on binding energies of oxygen adsorbates and directly associating the derived Sabatier volcano plot with calculated overpotential to forecast catalytic efficiency of cobalt porphyrin. This Sabatier volcano plot instructs that electron-withdrawing substituents mitigate the over-strong *OH intermediate adsorption by virtue of the decreased proportion of electrons in bonding orbital.
View Article and Find Full Text PDFReactivity and Enantioselectivity in NHC Organocatalysis Provide Evidence for the Complex Role of Modifications at the Secondary Sphere.
J Am Chem Soc
January 2023
Department of Chemistry, Ben-Gurion University of the Negev, Beer Sheva84105, Israel.
Secondary-sphere interactions are often harnessed to control reactivity and selectivity in organometallic and enzymatic catalysis. Yet, such strategies have only recently been explicitly applied in the context of organocatalytic systems. Although increased stability, reproducibility, and selectivity were obtained in previous work using this approach, the precise mechanistic pathway promoted by secondary-sphere modification in organocatalysis remained unclear.
View Article and Find Full Text PDFSecondary-sphere modification in proline catalysis: old friend, new connection.
Chem Commun (Camb)
February 2022
Department of Chemistry, Ben-Gurion University of the Negev, Beer Sheva, Israel.
In this work, we exploit our strategy of secondary-sphere modification of organocatalysts to improve the reactivity and selectivity of amino catalysts. Herein, the carboxylic acid moiety of proline was targeted as a site for modification under catalytic reaction conditions with boronic acids. Intermolecular aldol reactions between aromatic aldehydes and cyclopentanone were selected as a proof-of-concept because cyclopentanone as an aldol donor was often associated with decreased selectivity compared to its 6-membered ring analog, hexanone.
View Article and Find Full Text PDFSecondary Sphere Effects on Porous Polymeric Organocatalysts for CO Transformations: Subtle Modifications Resulting in Superior Performance.
ACS Appl Mater Interfaces
July 2020
Department of Chemistry, University of South Florida, 4202 East Fowler Avenue, Tampa, Florida 33620, United States.
Albeit harnessing secondary sphere interactions to exert control over the reaction outcomes has primarily been applied to enzymatic and organometallic catalysis, there are seldom any studies that introduce outer-sphere modifiers into organocatalysts. This is even less in the corresponding heterogeneous catalytic system. In this contribution, we experimentally and computationally investigate the role of secondary effects in the reactivity of bromide anions toward CO transformations.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!