scholarly journals Peroxyl, alkoxyl, and carbon-centered radical formation from organic hydroperoxides by chloroperoxidase

1989 ◽  
Vol 264 (14) ◽  
pp. 7889-7899
Author(s):  
W Chamulitrat ◽  
N Takahashi ◽  
R P Mason
Keyword(s):  
Radical Formation ◽  
Organic Hydroperoxides ◽  
Carbon Centered Radical

CO2 or SO2: Should It Stay or Should It Go?

2019 ◽  
Author(s):  
Gabriel dos Passos Gomes ◽  
Alexander Wimmer ◽  
Joel Smith ◽  
Burkhard König ◽  
Igor Alabugin
Keyword(s):  
Computational Analysis ◽  
Cross Coupling ◽  
Radical Formation ◽  
Structural Effects ◽  
Two Factors ◽  
Carbon Centered Radical ◽  
Dissociative Processes ◽  
Entropy Characteristic

<div><div><div><p>A broad computational analysis of carbon-centered radical formation via the loss of either CO2 or SO2 from the respective RXO2 radical precursors (X = C or S) reveals dramatic differences between these two types of dissociative processes. Whereas the C-C scission with the loss of CO2 is usually exothermic, the C-S scission with the loss of SO2 is generally endothermic. However, two factors can make the C-S scissions thermodynamically favorable: increased entropy, characteristic for the dissociative processes, and stereoelectronic influences of substituents. The threshold between endergonic and exergonic C-S fragmentations depends on subtle structural effects. In particular, the degree of fluorination in a radical precursor has a notable impact on the reaction outcome. This study aims to demystify the intricacies in reactivity regarding the generation of radicals from sulfinates and carboxylates, as related to their role in radical cross-coupling.</p></div></div></div>

scholarly journals CO2 or SO2: Should It Stay or Should It Go?

2019 ◽  
Author(s):  
Gabriel dos Passos Gomes ◽  
Alexander Wimmer ◽  
Joel Smith ◽  
Burkhard König ◽  
Igor Alabugin
Keyword(s):  
Computational Analysis ◽  
Cross Coupling ◽  
Radical Formation ◽  
Structural Effects ◽  
Two Factors ◽  
Carbon Centered Radical ◽  
Dissociative Processes ◽  
Entropy Characteristic

<div><div><div><p>A broad computational analysis of carbon-centered radical formation via the loss of either CO2 or SO2 from the respective RXO2 radical precursors (X = C or S) reveals dramatic differences between these two types of dissociative processes. Whereas the C-C scission with the loss of CO2 is usually exothermic, the C-S scission with the loss of SO2 is generally endothermic. However, two factors can make the C-S scissions thermodynamically favorable: increased entropy, characteristic for the dissociative processes, and stereoelectronic influences of substituents. The threshold between endergonic and exergonic C-S fragmentations depends on subtle structural effects. In particular, the degree of fluorination in a radical precursor has a notable impact on the reaction outcome. This study aims to demystify the intricacies in reactivity regarding the generation of radicals from sulfinates and carboxylates, as related to their role in radical cross-coupling.</p></div></div></div>

scholarly journals Strategic use of amino acid N-substituents to limit α-carbon-centered radical formation and consequent loss of stereochemical integrity

2003 ◽  
Vol 14 (19) ◽  
pp. 2919-2926 ◽  
Author(s):  
Anna K. Croft ◽  
Christopher J. Easton ◽  
Katherine Kociuba ◽  
Leo Radom
Keyword(s):  
Amino Acid ◽  
Radical Formation ◽  
Carbon Centered Radical

scholarly journals CO2 or SO2: Should It Stay or Should It Go

2018 ◽  
Author(s):  
Gabriel dos Passos Gomes ◽  
Alexander Wimmer ◽  
Joel Smith ◽  
Burkhard König ◽  
Igor Alabugin
Keyword(s):  
Computational Analysis ◽  
Cross Coupling ◽  
Radical Formation ◽  
Structural Effects ◽  
Stereoelectronic Effects ◽  
Two Factors ◽  
Carbon Centered Radical ◽  
Dissociative Processes ◽  
Entropy Characteristic

<p>A broad computational analysis of carbon-centered radical formation via the loss of either CO<sub>2</sub> or SO<sub>2</sub> from the respective RXO<sub>2</sub> radical precursors (X = C or S) reveals dramatic differences between these two types of dissociative processes. Whereas the C-C scission with the loss of CO<sub>2</sub> is usually exothermic, the C-S scission with the loss of SO<sub>2</sub> is generally endothermic. However, two factors can make the C-S scissions thermodynamically favorable: increased entropy, characteristic for the dissociative processes, and substituent stereoelectronic effects. The threshold between endergonic and exergonic C-S fragmentations depends on subtle structural effects. In particular, the degree of fluorination in a radical precursor has a notable impact on the reaction outcome. This study aims to demystify the intricacies in reactivity regarding the generation of radicals from sulfinates and carboxylates, as related to their role in radical cross-coupling.</p>

An Iron-Based Catalyst Enables The Enantioconvergent Synthesis of Chiral 1,1-Diarylalkanes Through a Suzuki-Miyaura Cross-Coupling Reaction

2020 ◽  
Author(s):  
Chet Tyrol ◽  
Nang Yone ◽  
Connor Gallin ◽  
Jeffery Byers
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Radical Intermediates ◽  
Cross Coupling Reactions ◽  
Cross Coupling Reaction ◽  
Boronic Esters ◽  
Carbon Centered Radical ◽  
Iron Based ◽  
High Yields

By using an iron-based catalyst, access to enantioenriched 1,1-diarylakanes was enabled through an enantioselective Suzuki-Miyaura crosscoupling reaction. The combination of a chiral cyanobis(oxazoline) ligand framework and 1,3,5-trimethoxybenzene additive were essential to afford high yields and enantioselectivities in cross-coupling reactions between unactivated aryl boronic esters and a variety of benzylic chlorides, including challenging ortho-substituted benzylic chloride substrates. Mechanistic investigations implicate a stereoconvergent pathway involving carbon-centered radical intermediates.

Photocatalytic Alkylation of Pyrroles and Indoles with α-Diazo Esters

2019 ◽  
Author(s):  
Łukasz Ciszewski ◽  
Jakub Durka ◽  
Dorota Gryko
Keyword(s):  
Aromatic Compounds ◽  
Reaction Pathway ◽  
Alkylating Agents ◽  
Catalytic Amount ◽  
Radical Formation ◽  
Reaction Selectivity ◽  
Diazo Esters ◽  
Electron Withdrawing Substituents

This article describes direct photoalkylation of electron-rich aromatic compounds with diazo compoiunds. C-2 alkylated indoles and pyrroles are obtained with good yields even though the photocatalyst (Ru(bpy)3Cl2) loading is as low as 0.075 mol %. For substrates bearing electron-withdrawing substituents the addition of a catalytic amount of N,N-dimethyl-4-methoxyaniline is required. Both EWG-EWG and EWG-EDG substituted diazo esters are suitable as alkylating agents. The reaction selectivity and mechanistic experiments suggest that carbenes/carbenoid intermediates are not involved in the reaction pathway, instead radical formation is proposed.

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