scholarly journals Origin of Enantioselectivity Reversal in Lewis Acid-Catalyzed Michael Additions Relying on the Same Chiral Source

2020 ◽  
Author(s):  
Paul S. Riehl ◽  
Alistair D. Richardson ◽  
Tatsuhiro Sakamoto ◽  
Jolene P. Reid ◽  
Corinna Schindler
Keyword(s):  
Asymmetric Catalysis ◽  
Lewis Acid ◽  
Chiral Ligand ◽  
Potential Significance ◽  
Kinetics And Thermodynamics ◽  
Important Concept ◽  
Michael Additions ◽  
Acid Catalyzed ◽  
Mechanistic Understanding

Enantiodivergence is an important concept in asymmetric catalysis that enables access to both enantiomers of a product relying on the same chiral source. This strategy is particularly appealing as an alternate approach when only one enantiomer of the required chiral ligand is readily accessible but both enantiomers of the product are desired. Despite their potential significance, general catalytic methods to induce reversal in enantioselectivity remain underdeveloped. Herein we report our studies focused on elucidating the origin of enantioselectivity reversal in Lewis acid-catalyzed Michael additions relying on the same enantiomer of ligand as the chiral source. Our results provide a detailed mechanistic understanding of this transformation based on experimental and computational investigations which reveal the important interplay between kinetics and thermodynamics responsible for the observed enantiodivergence.

scholarly journals Thermodynamic vs. Kinetic Control Enables Lewis Acid-Induced Enantioselectivity Reversal Relying on the Same Chiral Source

2020 ◽  
Author(s):  
Paul S. Riehl ◽  
Alistair D. Richardson ◽  
Tatsuhiro Sakamoto ◽  
Jolene P. Reid ◽  
Corinna Schindler
Keyword(s):  
Asymmetric Catalysis ◽  
Lewis Acid ◽  
Kinetic Control ◽  
Chiral Ligand ◽  
Potential Significance ◽  
Kinetics And Thermodynamics ◽  
Important Concept ◽  
Michael Additions ◽  
Acid Catalyzed ◽  
Mechanistic Understanding

Enantiodivergence is an important concept in asymmetric catalysis that enables access to both enantiomers of a product relying on the same chiral source. This strategy is particularly appealing as an alternate approach when only one enantiomer of the required chiral ligand is readily accessible but both enantiomers of the product are desired. Despite their potential significance, general catalytic methods to induce reversal in enantioselectivity remain underdeveloped. Herein we report our studies focused on elucidating the origin of enantioselectivity reversal in Lewis acid-catalyzed Michael additions relying on the same enantiomer of ligand as the chiral source. Our results provide a detailed mechanistic understanding of this transformation based on experimental and computational investigations which reveal the important interplay between kinetics and thermodynamics responsible for the observed enantiodivergence.

scholarly journals Thermodynamic vs. Kinetic Control Enables Lewis Acid-Induced Enantioselectivity Reversal Relying on the Same Chiral Source

2020 ◽  
Author(s):  
Paul S. Riehl ◽  
Alistair D. Richardson ◽  
Tatsuhiro Sakamoto ◽  
Jolene P. Reid ◽  
Corinna Schindler
Keyword(s):  
Asymmetric Catalysis ◽  
Lewis Acid ◽  
Kinetic Control ◽  
Chiral Ligand ◽  
Potential Significance ◽  
Kinetics And Thermodynamics ◽  
Important Concept ◽  
Michael Additions ◽  
Acid Catalyzed ◽  
Mechanistic Understanding

Enantiodivergence is an important concept in asymmetric catalysis that enables access to both enantiomers of a product relying on the same chiral source. This strategy is particularly appealing as an alternate approach when only one enantiomer of the required chiral ligand is readily accessible but both enantiomers of the product are desired. Despite their potential significance, general catalytic methods to induce reversal in enantioselectivity remain underdeveloped. Herein we report our studies focused on elucidating the origin of enantioselectivity reversal in Lewis acid-catalyzed Michael additions relying on the same enantiomer of ligand as the chiral source. Our results provide a detailed mechanistic understanding of this transformation based on experimental and computational investigations which reveal the important interplay between kinetics and thermodynamics responsible for the observed enantiodivergence.

scholarly journals Origin of Enantioselectivity Reversal in Lewis Acid-Catalysed Michael Additions Relying on the Same Chiral Source

2021 ◽  
Author(s):  
Paul S. Riehl ◽  
Alistair D. Richardson ◽  
Tatsuhiro Sakamoto ◽  
Jolene P. Reid ◽  
Corinna Schindler
Keyword(s):  
Asymmetric Catalysis ◽  
Lewis Acid ◽  
Metal Catalyst ◽  
Chiral Ligand ◽  
Specific Interactions ◽  
Reaction Parameter ◽  
Potential Significance ◽  
Important Concept ◽  
Michael Additions ◽  
Key Factor

Enantiodivergence is an important concept in asymmetric catalysis that enables access to both enantiomers of a product relying on the same chiral source as reagent. This strategy is particularly appealing as an alternate approach when only one enantiomer of the required chiral ligand is readily accessible but both enantiomers of the product are desired. Despite the potential significance, general catalytic methods to effectively reverse enantioselectivity by changing an achiral reaction parameter remain underdeveloped. Herein we report our studies focused on elucidating the origin of metal-controlled enantioselectivity reversal in Lewis acid-catalysed Michael additions. Rigorous experimental and computational investigations reveal that specific interactions between the substrate and ligand depending on the choice of metal catalyst are a key factor responsible for the observed enantiodivergence. This holds potential to further our understanding of and facilitate the design of future enantiodivergent transformations.

scholarly journals Origin of Enantioselectivity Reversal in Lewis Acid-Catalysed Michael Additions Relying on the Same Chiral Source

2021 ◽  
Author(s):  
Corinna Stefanie Schindler ◽  
Paul S. Riehl ◽  
Alistair D Richardson ◽  
Tatsuhiro Sakamoto ◽  
Jolene Reid
Keyword(s):  
Asymmetric Catalysis ◽  
Lewis Acid ◽  
Important Concept ◽  
Michael Additions

Enantiodivergence is an important concept in asymmetric catalysis that enables access to both enantiomers of a product relying on the same chiral source as reagent. This strategy is particularly appealing...

Catalytic Carbonyl-Olefin Metathesis of Aliphatic Ketones: Iron(III) HomoDimers as Lewis Acidic Superelectrophiles

2018 ◽  
Author(s):  
Haley Albright ◽  
Paul S. Riehl ◽  
Christopher C. McAtee ◽  
Jolene P. Reid ◽  
Jacob R. Ludwig ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Acid Activation ◽  
Lewis Acid Catalysts ◽  
Distinct Mode ◽  
Aliphatic Ketones ◽  
Carbon Carbon Bond ◽  
Metathesis Reactions ◽  
Acid Catalyzed

<div>Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond</div><div>formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly-bridged iron(III)-dimer as the active catalytic species. These “superelectrophiles” function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of “superelectrophiles” and broaden the current scope of catalytic carbonyl-olefin metathesis reactions.</div>

Enantioselective Syntheses of Flavonoid Diels-Alder Natural Products: A Review

2018 ◽  
Vol 15 (2) ◽  
pp. 221-229 ◽  
Author(s):  
Shah Bakhtiar Nasir ◽  
Noorsaadah Abd Rahman ◽  
Chin Fei Chee
Keyword(s):  
Natural Products ◽  
Organic Synthesis ◽  
Lewis Acid ◽  
Alder Reaction ◽  
Diels Alder ◽  
Enantioselective Synthesis ◽  
Chiral Ligand ◽  
Asymmetric Syntheses ◽  
Diels Alder Reaction ◽  
Enantioselective Syntheses

Background: The Diels-Alder reaction has been widely utilised in the syntheses of biologically important natural products over the years and continues to greatly impact modern synthetic methodology. Recent discovery of chiral organocatalysts, auxiliaries and ligands in organic synthesis has paved the way for their application in Diels-Alder chemistry with the goal to improve efficiency as well as stereochemistry. Objective: The review focuses on asymmetric syntheses of flavonoid Diels-Alder natural products that utilize chiral ligand-Lewis acid complexes through various illustrative examples. Conclusion: It is clear from the review that a significant amount of research has been done investigating various types of catalysts and chiral ligand-Lewis acid complexes for the enantioselective synthesis of flavonoid Diels-Alder natural products. The results have demonstrated improved yield and enantioselectivity. Much emphasis has been placed on the synthesis but important mechanistic work aimed at understanding the enantioselectivity has also been discussed.

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