Strategies to Generate Nitrogen-centered Radicals That May Rely on Photoredox Catalysis: Development in Reaction Methodology and Applications in Organic Synthesis

Chemical Reviews, Journal Year: 2021, Volume and Issue: 122(2), P. 2353 - 2428

Published: Oct. 8, 2021

For more than 70 years, nitrogen-centered radicals have been recognized as potent synthetic intermediates. This review is a survey designed for use by chemists engaged in target-oriented synthesis. summarizes the recent paradigm shift access to and application of N-centered enabled visible-light photocatalysis. broadens streamlines approaches many small molecules because photocatalysis conditions are mild. Explicit attention paid innovative advances N–X bonds radical precursors, where X = Cl, N, S, O, H. clarity, key mechanistic data noted, available. Synthetic applications limitations summarized illuminate tremendous utility photocatalytically generated radicals.

Language: Английский

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Reactivity of oximes for diverse methodologies and synthetic applications

Nature Synthesis, Journal Year: 2022, Volume and Issue: 1(1), P. 24 - 36

Published: Jan. 12, 2022

Language: Английский

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Photocatalytic C(sp³) radical generationviaC–H, C–C, and C–X bond cleavage

Chemical Science, Journal Year: 2022, Volume and Issue: 13(19), P. 5465 - 5504

Published: Jan. 1, 2022

C(sp 3 ) radicals (R˙) are of broad research interest and synthetic utility.

Language: Английский

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Catalyst Selection over an Electrochemical Reductive Coupling Reaction toward Direct Electrosynthesis of Oxime from NO_x and Aldehyde

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(9), P. 6294 - 6306

Published: Feb. 20, 2024

Aqueous electrochemical coupling reactions, which enable the green synthesis of complex organic compounds, will be a crucial tool in synthetic chemistry. However, lack informed approaches for screening suitable catalysts is major obstacle to its development. Here, we propose pioneering reductive reaction toward direct electrosynthesis oxime from NOx and aldehyde. Through integrating experimental theoretical methods, screen out optimal catalyst, i.e., metal Fe that facilitates enrichment C–N key intermediates, all leading high yields (e.g., ∼99% yield benzaldoxime) over Fe. With divided flow reactor, achieve benzaldoxime production 22.8 g h–1 gcat–1 ∼94% isolated yield. This work not only paves way industrial mass via but also offers references catalyst selection other reactions.

Language: Английский

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Visible-Light-Induced Energy-Transfer-Mediated Hydrofunctionalization and Difunctionalization of Unsaturated Compounds via Sigma-Bond Homolysis of Energy-Transfer Acceptors

ACS Catalysis, Journal Year: 2025, Volume and Issue: 15(3), P. 1854 - 1941

Published: Jan. 17, 2025

Over the past decade, visible-light-mediated energy-transfer (EnT) catalysis, particularly triplet–triplet (TTEnT) has emerged as a mild and environmentally friendly approach for diverse organic synthetic transformations. In contrast to photoredox which typically requires sacrificial electron donors or acceptors complete catalytic cycle, EnT photocatalysis generally proceeds with high atom economy while minimizing generation of wasteful byproducts. Furthermore, successful catalysis is contingent upon precise control redox potentials both photocatalysts substrates, strategies are primarily influenced by triplet energy compatibility between these entities. Considering growing importance photocatalysis, well hydrofunctionalization difunctionalization reactions in synthesis, this review systematically summarizes significant advancements EnT-enabled unsaturated compounds via sigma-bond homolysis over decade. Special emphasis placed on elucidating substrate scopes mechanistic scenarios. Additionally, discusses versatile applications methodologies addresses current challenges opportunities within evolving research field. This structured into six main categories based different types sigma-bonds undergoing homolysis. These include transformations mediated 1) N–O bond oxime esters other N,O-radical precursors; 2) N–S N-sulfonyl imines N,S-radical 3) chalcogen–chalcogen disulfides oxy/thio/selenosulfonates; 4) C–S tri/difluoromethylated sulfinates, acetylenic triflones, arylsulfonium salts; 5) C–X (X = halogen) halides; 6) acceptors. Through providing theoretical backgrounds along comprehensive overview currently employed acceptors, photosensitizers, contemporary EnT-induced compounds, aims serve an invaluable resource future innovations rapidly

Language: Английский

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Copper-Catalyzed Annulation of O-Acyl Oximes with Cyclic 1,3-Diones for the Synthesis of 7,8-Dihydroindolizin-5(6H)-ones and Cyclohexanone-Fused Furans

Organic Letters, Journal Year: 2023, Volume and Issue: 25(5), P. 838 - 842

Published: Jan. 27, 2023

A copper-catalyzed annulation of O-acyl oximes with cyclic 1,3-diones has been developed for the concise synthesis 7,8-dihydroindolizin-5(6H)-ones and cyclohexanone-fused furans through substituent-controlled selective radical coupling process. 2-Alkyl undergo C-C coupling, while 2-unsubstituted C-O coupling.

Language: Английский

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Recent Advances in N-O Bond Cleavage of Oximes and Hydroxylamines to Construct N-Heterocycle

Molecules, Journal Year: 2023, Volume and Issue: 28(4), P. 1775 - 1775

Published: Feb. 13, 2023

Oximes and hydroxylamines are a very important class of skeletons that not only widely exist in natural products drug molecules, but also synthon, which have been used industrial production. Due to weak N-O σ bonds oximes hydroxylamines, they can be easily transformed into other functional groups by bond cleavage. Therefore, the synthesis N-heterocycle using as nitrogen sources has attracted wide attention. Recent advances for through transition-metal-catalyzed radical-mediated cyclization classified type rings summarized. In this paper, recent cleavage reviewed. We hope review provides new perspective on field, reference develop environmentally friendly sustainable methods.

Language: Английский

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N‐Alkoxyphtalimides as Versatile Alkoxy Radical Precursors in Modern Organic Synthesis

Asian Journal of Organic Chemistry, Journal Year: 2022, Volume and Issue: 11(8)

Published: June 14, 2022

Abstract O‐substituted derivatives of N ‐hydroxyphthalimide (NHPI) have attracted much attention recently as synthetically available, stable, and convenient reagents for the generation free radicals under mild conditions. The single‐electron reduction by a photoredox catalyst or another reagent results in N−O bond cleavage an NHPI derivative with release that undergo selective synthetic transformations. Whereas ‐acyloxyphtalimides (NHPI esters) are well known C‐radical source due to facile one‐electron followed decarboxylation, ‐alkoxyphtalimides less studied radical precursors. present review shows effective free‐radical transformations starting from alkoxy radicals. Visible light induced reactions discussed first, these processes classified according way how intermediate transformed C‐centered radicals: via hydrogen atom transfer oxygen (HAT, including 1,5‐HAT, 1,2‐HAT, intermolecular HAT) β‐scission. Other photochemical alkoxyphthalimides non‐photochemical tin‐mediated separately.

Language: Английский

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Construction of N-Polyheterocycles by N-Heterocyclic Carbene Catalysis via a Regioselective Intramolecular Radical Addition/Cyclization Cascade

Organic Letters, Journal Year: 2022, Volume and Issue: 24(25), P. 4615 - 4619

Published: June 22, 2022

N-Polyheterocycles are rapidly accessed by N-heterocyclic carbene (NHC) catalysis through regioselective sequential radical addition/cyclization in the absence of any metals or oxidants. The transformation occurs under mild conditions and enjoys a wide substrate scope with excellent functional group compatibility. Furthermore, gram-scale synthesis is also conducted. Preliminary mechanistic studies reveal potential involvement an NHC cation intermediate.

Language: Английский

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CH‐Functionalization of Heterocycles with the Formation of C−O, C−N, C−S/Se, and C−P Bonds by Intermolecular Addition of Heteroatom‐Centered Radicals

Advanced Synthesis & Catalysis, Journal Year: 2023, Volume and Issue: 365(11), P. 1714 - 1755

Published: April 12, 2023

Abstract In the last decade, free radicals have found a wide application in functionalization of unsaturated compounds, such as alkenes, alkynes, and arenes, via free‐radical addition to carbon‐carbon π‐bonds. these processes, intermolecular attack on aromatic substrates represents challenge due relatively high resistance π‐system reactions comparison alkene C=C bonds. The heterocycles is especially interesting diversity their structures chemical properties well importance for medicinal chemistry, agrochemistry, materials science. Addition C‐centered widely known Minisci‐type well‐reviewed. this paper, we summarized main achievements less explored group processes: by heteroatom‐centered (O‐, N‐, S‐/Se‐, P‐radicals) with emphasis papers published after 2010. Literature analysis revealed strong trend towards usage electrochemistry photoredox‐catalysis generation recent years. remaining fundamental problem field lack experimental support proposed mechanisms frequent existence several plausible reaction pathways. progress mechanistic studies can significantly improve prediction optimal conditions depending structure.

Language: Английский

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