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>

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

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.

scholarly journals Nickel-Catalyzed 1,2-Diarylation of Simple Alkenyl Amides

2018 ◽  
Author(s):  
Joseph Derosa ◽  
Roman Kleinmans ◽  
Van Tran ◽  
Malkanthi Karunananda ◽  
Steven Wisniewski ◽  
...  
Keyword(s):  
Computational Analysis ◽  
Functional Group ◽  
Cross Coupling ◽  
Dimethyl Fumarate ◽  
Binding Mode ◽  
Wide Range ◽  
Boronic Esters ◽  
Optimized Conditions ◽  
Potential Substrate

A nickel-catalyzed conjunctive cross-coupling of simple alkenyl amides with aryl iodides and aryl boronic esters is reported. The reaction is enabled by an electron-deficient olefin (EDO) ligand, dimethyl fumarate, and delivers the desired 1,2-diarylated products with excellent regiocontrol. Under optimized conditions, a wide range of amides derived from 3-butenoic acid, 4-pentenoic acid, and allyl amine are compatible substrates. This methodology represents the first example of regiocontrolled 1,2-diarylation directed by a native amide functional group. Computational analysis sheds light on potential substrate binding mode and the role of EDO ligand in the reductive elimination step.

scholarly journals Nickel-Catalyzed 1,2-Diarylation of Simple Alkenyl Amides

2018 ◽  
Author(s):  
Joseph Derosa ◽  
Roman Kleinmans ◽  
Van Tran ◽  
Malkanthi Karunananda ◽  
Steven Wisniewski ◽  
...  
Keyword(s):  
Computational Analysis ◽  
Functional Group ◽  
Cross Coupling ◽  
Dimethyl Fumarate ◽  
Binding Mode ◽  
Wide Range ◽  
Boronic Esters ◽  
Optimized Conditions ◽  
Potential Substrate

A nickel-catalyzed conjunctive cross-coupling of simple alkenyl amides with aryl iodides and aryl boronic esters is reported. The reaction is enabled by an electron-deficient olefin (EDO) ligand, dimethyl fumarate, and delivers the desired 1,2-diarylated products with excellent regiocontrol. Under optimized conditions, a wide range of amides derived from 3-butenoic acid, 4-pentenoic acid, and allyl amine are compatible substrates. This methodology represents the first example of regiocontrolled 1,2-diarylation directed by a native amide functional group. Computational analysis sheds light on potential substrate binding mode and the role of EDO ligand in the reductive elimination step.

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

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.

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