852049-32-2Relevant academic research and scientific papers
Stereochemical diversity in chiral ligand design: Discovery and optimization of catalysts for the enantioselective addition of allylic halides to aldehydes
Lee, Jae-Young,Miller, Jeremie J.,Hamilton, Steven S.,Sigman, Matthew S.
, p. 1837 - 1839 (2005)
(Chemical Equation Presented) We have identified a new set of stereochemically diverse oxazoline ligands derived from simple amino acids that promote the Cr-catalyzed enantioselective addition of allylic halides to aldehydes in up to 95% ee. The Cr-cataly
Chiral oxazoline NNP type ligands as well as synthesis method and application thereof
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, (2017/08/28)
The invention relates to chiral oxazoline NNP type ligands as well as a synthesis method and an application thereof. The ligands adopt the structure shown in general formula 1 or 2. During preparation, a chiral ligand 1 and a chiral ligand 2 are prepared from Fmoc-Cl and a chiral amino acid compound 3 used as initial raw materials through multi-step reactions. The ligands can be applied to catalytic synthesis of chiral beta ketone ester fluoride and synthesis of propanedione derivatives and chiral malonate derivatives through palladium-catalyzed asymmetric allyl substitution reactions. Compared with the prior art, the reaction condition is mild, operation is easy, repeatability is good, mass preparation can be realized, and the prepared catalyst has higher ee value and yield when applied to beta ketone ester fluoridation and palladium-catalyzed asymmetric allyl substitution reactions.
Examination of the role of Taft-type steric parameters in asymmetric catalysis
Sigman, Matthew S.,Miller, Jeremie J.
supporting information; experimental part, 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.
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 (2008/12/20)
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
