Radical NHC Catalysis

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(19), P. 11984 - 11999

Published: Sept. 19, 2022

Radical/radical cross-coupling reactions represent an efficient and straightforward approach for the construction of chemical bonds accordingly have drawn increasing attention over past decades. In order to achieve synthetically useful transformations, a persistent radical should be coupled with transient in accordance effect (PRE). However, known radicals outnumber by far types free radicals, which limits widespread application PRE, until today. Thus, development between has been focus, meanwhile transition-metal catalysis successfully implemented artificially prolong lifetimes, allowing their utilization formal radical/radical cross-couplings. Complementary research field recently uncovered that organocatalytically generated NHC-derived ketyl are type catalytically radicals. NHC-catalyzed transformations aldehydes carboxylic acid derivatives enabled disclosure ever-increasing number interesting reactions, different from traditional ionic processes, offering otherwise inaccessible activation modes. These discoveries opened door NHC organocatalysis manipulation reactions. Due its obvious potential synthetic organic chemistry, it is timely provide perspective on this emerging field.

Language: Английский

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Single-electron carbene catalysis in redox processes

Trends in Chemistry, Journal Year: 2022, Volume and Issue: 4(4), P. 277 - 290

Published: Feb. 11, 2022

Language: Английский

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Carbene and photocatalyst-catalyzed decarboxylative radical coupling of carboxylic acids and acyl imidazoles to form ketones

Nature Communications, Journal Year: 2022, Volume and Issue: 13(1)

Published: May 23, 2022

The carbene and photocatalyst co-catalyzed radical coupling of acyl electrophile a precursor is emerging as attractive method for ketone synthesis. However, previous reports mainly limited to prefunctionalized precursors two-component coupling. Herein, an N-heterocyclic catalyzed decarboxylative carboxylic acids imidazoles disclosed, in which the are directly used precursors. could also be generated situ by reaction acid with CDI thus furnishing formally two acids. In addition, successfully extended three-component using alkene third partner via relay process. mild conditions, operational simplicity, use reacting partners make our powerful strategy construction complex ketones from readily available starting materials, late-stage modification natural products medicines.

Language: Английский

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Critical Assessment of the Reducing Ability of Breslow‐type Derivatives and Implications for Carbene‐Catalyzed Radical Reactions**

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(51), P. 26783 - 26789

Published: Oct. 15, 2021

Abstract We report the synthesis of acyl azolium salts stemming from thiazolylidenes C NS , triazolylidenes TN mesoionic carbenes MIC and generation their corresponding radicals enolates, covering about 60 Breslow‐type derivatives. This study highlights role additives in redox behavior these compounds unveils several critical misconceptions radical transformations aldehyde derivatives under N‐heterocyclic carbene catalysis. In particular, reducing ability enolates has been dramatically underestimated case biomimetic . contrast with previous electrochemical studies, we show that catalytic intermediates can transfer electrons to iodobenzene within minutes at room temperature. Enols derived are not previously claimed super electron donors, although enolate powerful agents.

Language: Английский

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N-Heterocyclic Carbene-Photocatalyzed Tricomponent Regioselective 1,2-Diacylation of Alkenes Illuminates the Mechanistic Details of the Electron Donor–Acceptor Complex-Mediated Radical Relay Processes

ACS Catalysis, Journal Year: 2021, Volume and Issue: 12(1), P. 285 - 294

Published: Dec. 15, 2021

Progress in the development of photocatalytic reactions requires a detailed understanding mechanisms underpinning observed reactivity, yet mechanistic details many systems, especially those that involve electron donor–acceptor complexes, have remained elusive. We report herein and combined computational study alkene 1,2-diacylation enables regioselective installation two different acyl groups, establishing direct, tricomponent access to 1,4-diketones, key intermediates heterocyclic medicinal chemistry. The studies revealed central role complex formed from an N-heterocyclic carbene (NHC) catalyst-derived intermediate transfer reagent, providing description structural electronic factors determining characteristics photoinduced charge-transfer process mediates transformation. in-depth investigation also illuminated roles other radical donors relevant catalytic activities carbenes reactions.

Language: Английский

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Oxidative Radical NHC Catalysis: Divergent Difunctionalization of Olefins through Intermolecular Hydrogen Atom Transfer

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(44)

Published: Sept. 9, 2022

Oxidative N-heterocyclic carbene (NHC) organocatalysis, typically leading to the formation of acyl azolium reactive intermediates, constitutes one most important activation strategies for NHC-catalyzed chemical transformations. Here, we report an unprecedented oxidative radical NHC catalysis by using peroxyester as external single-electron oxidant realize divergent difunctionalization olefins. The key success this chemistry is catalytic generation oxygen radicals that could trigger intermolecular hydrogen atom transfer activate inert C-H bonds, thereby enabling productive relay process. With protocol, commonly used general chemicals serve precursors allow efficient synthesis value-added products in a straightforward and cost-effective manner. Preliminary mechanistic investigations, including control experiments DFT calculations, shed light on organocatalytic reaction mechanism.

Language: Английский

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Three-component carboacylation of alkenes via cooperative nickelaphotoredox catalysis

Chemical Science, Journal Year: 2022, Volume and Issue: 13(24), P. 7256 - 7263

Published: Jan. 1, 2022

Various commercially available acyl chlorides, aldehydes, and alkanes were exploited for versatile three-component 1,2-carboacylations of alkenes to forge two vicinal C-C bonds through the cooperative action nickel sodium decatungstate catalysis. A wealth ketones with high levels structural complexity was rapidly obtained via direct functionalization C(sp2)/C(sp3)-H in a modular manner. Furthermore, regioselective late-stage modification natural products showcased practical utility strategy, generally featuring resource economy ample substrate scope.

Language: Английский

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N-Heterocyclic-Carbene-Catalyzed C–H Acylation via Radical Relay

Organic Letters, Journal Year: 2022, Volume and Issue: 24(3), P. 944 - 948

Published: Jan. 20, 2022

A method of N-fluorocarboxamide-directed N-heterocyclic-carbene (NHC)-catalyzed benzylic C-H acylation with aldehydes via the hydrogen atom transfer strategy is disclosed. This transformation involves a sequence single-electron transfer, 1,5-hydrogen and radical cross-coupling steps. offers facile access to various highly functionalized ketones exhibits good chemical yields functional group tolerance.

Language: Английский

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Radical Acylalkylation of 1,3-Enynes To Access Allenic Ketones via N-Heterocyclic Carbene Organocatalysis

The Journal of Organic Chemistry, Journal Year: 2022, Volume and Issue: 87(8), P. 5229 - 5241

Published: March 29, 2022

An N-heterocyclic carbene organocatalytic 1,4-difunctionalization of 1,3-enynes was developed. This strategy suitable for a broad spectrum substrates to efficiently synthesize allenic ketones bearing diverse substituents. Preliminary mechanistic studies suggest radical reaction pathway this acylalkylation process.

Language: Английский

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α-Amino Radical-Mediated Difunctionalization of Alkenes with Polyhaloalkanes and N-Heteroarenes

Organic Letters, Journal Year: 2023, Volume and Issue: 25(11), P. 1994 - 1998

Published: March 15, 2023

Herein, we report a mild and practical protocol for the α-perchloroalkyl β-heteroarylation of alkenes using available chloroform as dichloromethyl source via α-amino radical-mediated halogen-atom transfer. Various substrates are compatible under reaction conditions, providing corresponding products in moderate to good yields. This strategy gives an efficient convenient method introduction chloroalkyl motifs into N-heteroarenes. The control experiment demonstrates that radical generated situ is key intermediate transformation.

Language: Английский

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