1008530-29-7Relevant academic research and scientific papers
Quantitatively correlating the effect of ligand-substituent size in asymmetric catalysis using linear free energy relationships
Miller, Jeremie J.,Sigman, Matthew S.
, p. 771 - 774 (2008)
Is bigger better? By systematically evaluating the size of the substituent G in a modular ligand (see picture), a linear free energy relationship was observed relating the product enantiomeric ratio to steric parameters developed by Charton. The reaction
Examination of the role of Taft-type steric parameters in asymmetric catalysis
Sigman, Matthew S.,Miller, Jeremie J.
supporting information; scheme or table, p. 7633 - 7643 (2009/12/27)
(Chemical Equation Presented) 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.
