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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Photoinduced Acylations Via Azolium-Promoted Intermolecular Hydrogen Atom Transfer

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(3), P. 1535 - 1541

Published: Jan. 10, 2023

Photoinduced hydrogen atom transfer (HAT) has been developed as a powerful tool to generate synthetically valuable radical species. The direct photoexcitation of ketones known promote HAT or acyl radicals through Norrish-type pathways, but these modalities remain severely limited by side reactions. We report herein catalyst- and transition metal-free method for the acylation C-H bonds that leverages unique properties stable, isolable azolium Specifically, salts are shown undergo an intermolecular regioselective upon LED irradiation with range substrates bearing active followed C-C bond formation afford ketones. Experimental computational studies support facile intersystem crossing access triplet diradical species selective radical-radical cross-coupling.

Language: Английский

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Recent advances in combining photo- and N-heterocyclic carbene catalysis

Chemical Science, Journal Year: 2023, Volume and Issue: 14(46), P. 13367 - 13383

Published: Jan. 1, 2023

This review summarizes recent advances in combining photo- and N-heterocyclic carbene catalysis, as well provides an outlook on future opportunities challenges.

Language: Английский

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Radical Reactions with N-Heterocyclic Carbene (NHC)-Derived Acyl Azoliums for Access to Multifunctionalized Ketones

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(11), P. 8270 - 8293

Published: May 13, 2024

As one of the most important key intermediates, NHC-bound acylazolium-based ionic transformations have been intensively explored in past two decades. With expeditious development NHC-catalyzed radical recent years, acylazolium chemistry has reached another level, with number relevant publications increasing significantly. However, a summary focused on acylations NHC-derived acyl azoliums classified according to mechanistic difference not reported. Such detailed classification and deep analysis provide opportunities for better understanding history trend this field. In review, reactions N-heterocyclic carbene (NHC)-derived are systematically introduced. The achievements challenges within area also summarized discussed at end.

Language: Английский

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Branched-Selective Hydroacylation of Alkenes via Photoredox Cobalt and N-Heterocyclic Carbene Cooperative Triple Catalysis

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(24), P. 15241 - 15248

Published: Nov. 29, 2022

A Markovnikov-selective hydroacylation of alkenes has been achieved via the synergistic merger cobalt, photoredox and N-heterocyclic carbene catalysis. The closely incorporated catalytic cycles allow for Co(III) generation by photochemical oxidation instead chemical oxidants or anodizing process. This mild, operationally simple protocol converts a wide variety commercially available aroyl fluorides into corresponding ketones in high yield with branched selectivity.

Language: Английский

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State-of-the-art, challenges and prospects of heterogeneous tandem photocatalysis

Coordination Chemistry Reviews, Journal Year: 2023, Volume and Issue: 492, P. 215276 - 215276

Published: June 10, 2023

Language: Английский

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Photoinduced Electron Transfer from Xanthates to Acyl Azoliums: Divergent Ketone Synthesis via N‐Heterocyclic Carbene Catalysis

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(32)

Published: June 12, 2023

Considering the prevalence of alcohols and carboxylic acids, their fragment cross-coupling reactions could hold significant implications in organic synthesis. Herein, we report a versatile method for synthesizing diverse range ketones from acid derivatives via N-heterocyclic carbene (NHC) catalysis. Mechanistic investigations revealed that photoexcited xanthates acyl azoliums undergo single electron transfer (SET) under photocatalyst-free conditions, generating NHC-derived ketyl radicals alkyl radicals. These open-shell intermediates subsequently radical-radical reaction, yielding valuable ketones. Furthermore, this approach can be employed three-component involving alkenes enynes, resulting structurally cross-coupled The unified strategy offers unique opportunity coupling derivatives, accommodating functional groups even complex settings.

Language: Английский

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N-heterocyclic carbene- and organic photoredox-catalysed meta-selective acylation of electron-rich arenes

Nature Synthesis, Journal Year: 2023, Volume and Issue: 2(11), P. 1037 - 1045

Published: Aug. 3, 2023

Language: Английский

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Light‐Driven Enantioselective Carbene‐Catalyzed Radical‐Radical Coupling

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(49)

Published: Oct. 17, 2023

Abstract An enantioselective carbene‐catalyzed radical‐radical coupling of acyl imidazoles and racemi c Hantzsch esters is disclosed. This method involves the an N‐heterocyclic carbene‐derived ketyl radical a secondary sp 3 ‐carbon allows access to chiral α‐aryl aliphatic ketones in moderate‐to‐good yields enantioselectivities without any competitive epimerization. The utility this protocol highlighted by late‐stage functionalization various pharmaceutical compounds further demonstrated transformation enantioenriched products biologically relevant molecules. Computational investigations reveal carbene controls double‐facial selectivity alkyl radicals, respectively.

Language: Английский

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Mesoionic Carbene‐Catalyzed Formyl Alkylation of Aldehydes

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(24)

Published: April 18, 2023

Ketones are among the most useful functional groups in organic synthesis, and they commonly encountered a broad range of compounds with various applications. Herein, we describe mesoionic carbene-catalyzed coupling reaction aldehydes non-activated secondary even primary alkyl halides. This metal-free method utilizes deprotonated Breslow intermediates derived from carbenes (MICs), which act as super electron donors induce single-electron reduction mild has substrate scope tolerates many groups, allows to prepare diversity simple ketones well bio-active molecules by late-stage functionalization.

Language: Английский

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