Related Experiment Video
Updated: Jun 19, 2026

Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks (MOFs)
Published on: January 17, 2020
Examination of the role of Taft-type steric parameters in asymmetric catalysis
Matthew S Sigman1, Jeremie J Miller
1Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, USA. sigman@chem.utah.edu
Abstract:
We report the use of Taft steric parameters to correlate the substituent size of a ligand with the enantiomeric ratio of a reaction. Linear free energy relationships can be constructed by plotting the log of enantiomeric ratio (er) versus the steric parameters reported by Taft and modified by Charton. Successful correlations were found for aldehyde and ketone allylation under NHK conditions using modular oxazoline ligands developed in our laboratory. Using these correlations, ligands were designed and evaluated for carbonyl allylation reactions. A break in the Charton plot results and is attributed to a global structural change in the catalyst. Additionally, several previously reported enantioselective reactions are analyzed resulting in excellent correlations for both catalysts and substrates. Finally, limitations and issues are presented with illustrative examples.
More Related Videos
Related Concept Videos
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
Woodward–Hoffmann Selection Rules and Microscopic Reversibility
Regioselectivity and Stereochemistry of Hydroboration
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Radical Reactivity: Steric Effects
Along with electronic factors, steric factors also account...
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
Sharpless Epoxidation

