scholarly journals Mechanistic Studies of Single-Step Styrene Production Using a Rhodium(I) Catalyst

2017 ◽  
Vol 139 (4) ◽  
pp. 1485-1498 ◽  
Author(s):  
Benjamin A. Vaughan ◽  
Sarah K. Khani ◽  
J. Brannon Gary ◽  
James D. Kammert ◽  
Michael S. Webster-Gardiner ◽  
...  
Keyword(s):  
Single Step ◽  
Mechanistic Studies ◽  
Styrene Production

scholarly journals Cobalt Hydride Oxidase Catalysis Enabled Hydroamination of Unactivated Olefins

2021 ◽  
Author(s):  
Wei-Ting Ye ◽  
Rong Zhu
Keyword(s):  
Building Blocks ◽  
Single Step ◽  
Tertiary Amines ◽  
Mechanistic Studies ◽  
Organic Transformations ◽  
Design Elements ◽  
Alkyl Radicals ◽  
Solvent Free Conditions ◽  
Oxidative Processes ◽  
Nitrogen Nucleophiles

Dioxygen is an abundant, selective, and sustainable oxidant that is considered ideal for organic transformations. Oxidative processes using dioxygen as the electron acceptor without oxygen atom incorporation into the substrate are often referred to as oxidase reactions. However, the ground state triplet nature of dioxygen makes such a synthetically valuable pathway incompatible with simple free alkyl radicals, a ubiquitous class of reactive intermediates in the daily synthesis of pharmaceuticals, agrochemicals, and complex natural products. Here we report that a combination of strong cage effect and bimetallic radical-polar crossover successfully addresses this problem, and opens up an oxidase pathway in cobalt hydride catalysis. This leads to a general and chemoselective method that tackles several key challenges in catalytic hydroamination, a fundamental transformation for amine synthesis. Under balloon pressure of dioxygen at ambient temperature, we demonstrate single-step intra- and intermolecular formal addition of a variety of nitrogen nucleophiles, including free amines, sulfonamides, amides, and carbamates, to unactivated alkenes in the presence of a silane, under solvent-free conditions. Important medicinal chemistry building blocks such as a-branched tertiary amines can be easily accessed, which are often difficult targets otherwise due to their steric hindrance and reducing nature. Mechanistic studies including stoichiometric experiments with well-defined organocobalt complexes provide support for the key hypothesis, which points the way to the development of sustainable processes involving other nucleophiles based on the same design elements.

A rhodium catalyst for single-step styrene production from benzene and ethylene

Science ◽  
2015 ◽  
Vol 348 (6233) ◽  
pp. 421-424 ◽  
Author(s):  
B. A. Vaughan ◽  
M. S. Webster-Gardiner ◽  
T. R. Cundari ◽  
T. B. Gunnoe
Keyword(s):  
Single Step ◽  
Rhodium Catalyst ◽  
Styrene Production

scholarly journals Chemoselective α-Sulfidation of Amides Using Sulfoxide Reagents

2020 ◽  
Author(s):  
Mario Leypold ◽  
Kyan A. D’Angelo ◽  
Mohammad Movassaghi
Keyword(s):  
Critical Role ◽  
Single Step ◽  
Mechanistic Studies ◽  
Selective Functionalization ◽  
Sulfonium Ions ◽  
Activation Conditions ◽  
Tertiary Amides ◽  
Amide Activation

The direct α-sulfidation of tertiary amides using sulfoxide reagents under electrophilic amide activation conditions is described. Employing readily available reagents, selective functionalization takes place to generate isolable sulfonium ions en route to α-sulfide amides. Mechanistic studies support the critical role of activated sulfoxides that promote the desired transformation. For benzylic amide substrates, a single-step protocol featuring a spontaneous dealkylation step of a sulfonium ion intermediate was developed.

scholarly journals Chemoselective α-Sulfidation of Amides Using Sulfoxide Reagents

2020 ◽  
Author(s):  
Mario Leypold ◽  
Kyan A. D’Angelo ◽  
Mohammad Movassaghi
Keyword(s):  
Critical Role ◽  
Single Step ◽  
Mechanistic Studies ◽  
Selective Functionalization ◽  
Sulfonium Ions ◽  
Activation Conditions ◽  
Tertiary Amides ◽  
Amide Activation

The direct α-sulfidation of tertiary amides using sulfoxide reagents under electrophilic amide activation conditions is described. Employing readily available reagents, selective functionalization takes place to generate isolable sulfonium ions en route to α-sulfide amides. Mechanistic studies support the critical role of activated sulfoxides that promote the desired transformation. For benzylic amide substrates, a single-step protocol featuring a spontaneous dealkylation step of a sulfonium ion intermediate was developed.

scholarly journals Cobalt Hydride Oxidase Catalysis Enabled Hydroamination of Unactivated Olefins

2021 ◽  
Author(s):  
Wei-Ting Ye ◽  
Rong Zhu
Keyword(s):  
Building Blocks ◽  
Single Step ◽  
Tertiary Amines ◽  
Mechanistic Studies ◽  
Organic Transformations ◽  
Design Elements ◽  
Alkyl Radicals ◽  
Solvent Free Conditions ◽  
Oxidative Processes ◽  
Nitrogen Nucleophiles

Dioxygen is an abundant, selective, and sustainable oxidant that is considered ideal for organic transformations. Oxidative processes using dioxygen as the electron acceptor without oxygen atom incorporation into the substrate are often referred to as oxidase reactions. However, the ground state triplet nature of dioxygen makes such a synthetically valuable pathway incompatible with simple free alkyl radicals, a ubiquitous class of reactive intermediates in the daily synthesis of pharmaceuticals, agrochemicals, and complex natural products. Here we report that a combination of strong cage effect and bimetallic radical-polar crossover successfully addresses this problem, and opens up an oxidase pathway in cobalt hydride catalysis. This leads to a general and chemoselective method that tackles several key challenges in catalytic hydroamination, a fundamental transformation for amine synthesis. Under balloon pressure of dioxygen at ambient temperature, we demonstrate single-step intra- and intermolecular formal addition of a variety of nitrogen nucleophiles, including free amines, sulfonamides, amides, and carbamates, to unactivated alkenes in the presence of a silane, under solvent-free conditions. Important medicinal chemistry building blocks such as a-branched tertiary amines can be easily accessed, which are often difficult targets otherwise due to their steric hindrance and reducing nature. Mechanistic studies including stoichiometric experiments with well-defined organocobalt complexes provide support for the key hypothesis, which points the way to the development of sustainable processes involving other nucleophiles based on the same design elements.

ChemInform Abstract: A Rhodium Catalyst for Single-Step Styrene Production from Benzene and Ethylene.

ChemInform ◽  
2015 ◽  
Vol 46 (39) ◽  
pp. no-no
Author(s):  
Benjamin A. Vaughan ◽  
Michael S. Webster-Gardiner ◽  
Thomas R. Cundari ◽  
T. Brent Gunnoe
Keyword(s):  
Single Step ◽  
Rhodium Catalyst ◽  
Styrene Production

V884: Demonstration of a Novel Single-Step Percutaneous Access Sheath for Nephrostolithotomy: A Video Presentation

2005 ◽  
Vol 173 (4S) ◽  
pp. 240-240
Author(s):  
Premal J. Desai ◽  
David A. Hadley ◽  
Lincoln J. Maynes ◽  
D. Duane Baldwin
Keyword(s):  
Single Step ◽  
Video Presentation ◽  
Percutaneous Access ◽  
Access Sheath
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