Visible Light-Driven Radical-Mediated C–C Bond Cleavage/Functionalization in Organic Synthesis

Chemical Reviews, Journal Year: 2020, Volume and Issue: 121(1), P. 506 - 561

Published: May 29, 2020

Thermal C–C bond cleavage reactions allow the construction of structurally diverse molecular skeletons via predictable and efficient reorganizations. Visible light photoredox-catalyzed radical-mediated have recently emerged as a powerful alternative method for overcoming thermodynamic kinetic barrier in scaffolds. In recent years, plethora elegant useful been invented, products are sometimes otherwise inaccessible by classic thermal reactions. Considering great influence synthetic potential these reactions, we provide summary state art visible light-driven cleavage/functionalization strategies with specific emphasis on working models. We hoped that this review will be medicinal organic chemists inspire further reaction development interesting area.

Language: Английский

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When Light Meets Nitrogen-Centered Radicals: From Reagents to Catalysts

Accounts of Chemical Research, Journal Year: 2020, Volume and Issue: 53(5), P. 1066 - 1083

Published: April 14, 2020

ConspectusNitrogen-centered radicals (NCRs) are a versatile class of highly reactive species that have longer history than the classical carbon-based in synthetic chemistry. Depending on N-hybridization and substitution patterns, NCRs can serve as electrophiles or nucleophiles to undergo various radical transformations. Despite their power, progress nitrogen-radical chemistry is still slow compared with popularity carbon radicals, considerable potential has been largely underexplored, which is, concluded by Zard, mainly hampered "a dearth convenient access these lack awareness pertaining reactivity".Over past decade, visible-light photoredox catalysis established powerful toolbox chemists use generate diverse range intermediates from native organic functional groups via single electron transfer process energy under mild reaction conditions. This catalytic strategy typically obviates need for external stoichiometric activation reagents toxic initiators often enables traditionally inaccessible ionic chemical reactions. On basis our long-standing interest nitrogen catalysis, we emphasized tactic discover develop novel methods generating controlled fashion applications. In this Account, describe recent advances development visible-light-driven photoredox-catalyzed generation applications.Inspired natural biological proton-coupled (PCET) process, first developed oxidative deprotonation activate N–H bonds hydrazones, benzamides, sulfonamides give corresponding With species, then achieved 5-exo 6-endo cyclizations well cascade reactions regioselective manner, providing variety potentially useful heterocycles. To further expand repertoire possible NCRs, also revealed iminyl derived O-acyl cycloalkanone oxime esters, facile ring-opening C–C bond cleavage cyanoalkyl radicals. These newly formed bond-forming allow synthesis distally functionalized alkyl nitriles. Stimulated studies, wide copper-catalyzed cross-coupling Because inherent transient properties, heteroatom-centered underexplored synthesis. Building understanding fundamental time concept NCR covalent involves situ-photogenerated allyl sulfones, vinylcyclopropanes, N-tosyl vinylaziridines. thus enabled efficient difunctionalization alkenes late-stage modification complex biologically active molecules.In panoramic picture contributions since 2014 application systems field studies provide not only functionally rich molecules but some insight into exploration new reactivity modes NCRs.

Language: Английский

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Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Chemical Reviews, Journal Year: 2021, Volume and Issue: 122(2), P. 2017 - 2291

Published: Nov. 23, 2021

We present here a review of the photochemical and electrochemical applications multi-site proton-coupled electron transfer (MS-PCET) in organic synthesis. MS-PCETs are redox mechanisms which both an proton exchanged together, often concerted elementary step. As such, MS-PCET can function as non-classical mechanism for homolytic bond activation, providing opportunities to generate synthetically useful free radical intermediates directly from wide variety common functional groups. introduction practitioner’s guide reaction design, with emphasis on unique energetic selectivity features that characteristic this class. then chapters oxidative N–H, O–H, S–H, C–H homolysis methods, generation corresponding neutral species. Then, reductive PCET activations involving carbonyl, imine, other X═Y π-systems, heteroarenes, where ketyl, α-amino, heteroarene-derived radicals be generated. Finally, we asymmetric catalysis materials device applications. Within each chapter, subdivide by group undergoing homolysis, thereafter type transformation being promoted. Methods published prior end December 2020 presented.

Language: Английский

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Transition Metal-Catalyzed Organic Reactions under Visible Light: Recent Developments and Future Perspectives

ACS Catalysis, Journal Year: 2020, Volume and Issue: 10(16), P. 9170 - 9196

Published: July 20, 2020

The development of transition metal (TM) catalysis for organic synthesis under visible light without recourse to typical photoredox catalysts has become a rapidly growing area research and been actively explored in the past several years. Distinct from extensively developed catalysis, which photocatalyst generally does not directly participate bond-forming process, photocatalyst/TM synergistic absorbs photon energy transfers TM catalyst through redox or transfer this Review focuses on summarizing recent developments photocatalytic reactions that use complexes both absorb catalytic bond formation involving covalently bonded intermediate. contents are categorized by used (Pd, Cu, Co, Ni, Mn, Au, Rh, Fe, Ru), with descending sequence according number examples reported each metal, provide an overview April 2020. Future perspectives personal opinions regarding expanding field also discussed.

Language: Английский

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Hydroxylamine Derivatives as Nitrogen‐Radical Precursors in Visible‐Light Photochemistry

Chemistry - A European Journal, Journal Year: 2018, Volume and Issue: 24(47), P. 12154 - 12163

Published: May 22, 2018

In recent years, hydroxylamines derivatives have been exploited as nitrogen-radical precursors in visible-light photochemistry. Their ability to serve electrophores redox chemistry has propelled the development of many novel transformations. Fundamental mechanistic aspects well importance preparation nitrogen-containing molecules will be highlighted.

Language: Английский

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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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Cleavage of Carbon–Carbon σ-Bonds of Four-Membered Rings

Chemical Reviews, Journal Year: 2020, Volume and Issue: 121(1), P. 264 - 299

Published: Sept. 23, 2020

This article reviews synthetic transformations involving cleavage of a carbon-carbon bond four-membered ring, with particular focus on the examples reported during period from 2011 to end 2019. Most significant is progress catalytic reactions oxidative addition bonds onto transition metals or β-carbon elimination metal alkoxides. When they are looked at perspectives, offer unique and efficient methods build complex natural products structures that difficult construct by conventional methods. On other hand, β-scission radical intermediates has also attracted increasing attention as an alternative elementary step cleave bonds. Its site-selectivity often complementary metal-catalyzed reactions. In addition, Lewis acid-mediated thermally induced ring-opening cyclobutanone derivatives garnered renewed attention. whole, these demonstrate potentials structurally strained ring compounds for construction organic skeletons.

Language: Английский

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Copper‐Catalyzed Radical Cross‐Coupling of Redox‐Active Oxime Esters, Styrenes, and Boronic Acids

Angewandte Chemie International Edition, Journal Year: 2018, Volume and Issue: 57(47), P. 15505 - 15509

Published: Oct. 8, 2018

A visible-light-driven, copper-catalyzed three-component radical cross-coupling of oxime esters, styrenes, and boronic acids has been developed. Key steps this protocol involve catalytic generation an iminyl from a redox-active ester subsequent C-C bond cleavage to generate cyanoalkyl radical. Upon its addition styrene, the newly formed benzylic undergoes coupling with boronic-acid-derived ArCuII complex achieve 1,1-diarylmethane-containing alkylnitriles.

Language: Английский

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Direct C–H Cyanoalkylation of Quinoxalin-2(1H)-ones via Radical C–C Bond Cleavage

Organic Letters, Journal Year: 2018, Volume and Issue: 20(4), P. 1034 - 1037

Published: Jan. 24, 2018

An efficient synthesis of cyanoalkylated heteroarenes via iron-catalyzed direct C–H cyanoalkylation has been developed. Structurally diverse cyanoalkyl motifs generated through C–C bond cleavage cyclobutanone oxime esters have introduced into quinoxalin-2(1H)-ones, flavone, benzothiazoles, and caffeine in good to excellent yields. Remarkably, less-strained cyclopentanone unstrained cyclohexanone were also amenable substrates this reaction.

Language: Английский

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Radical‐Promoted C−C Bond Cleavage: A Deconstructive Approach for Selective Functionalization

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 58(40), P. 14044 - 14054

Published: June 6, 2019

Abstract Just as “Deconstructivism” appeared a novel movement in architecture the 1980s, deconstructive approaches have recently emerged excellent strategies for scaffold hopping modifications chemistry. The deconstruction and functionalization of cyclic molecules mainly involves cleavage carbon–carbon (C−C) bond followed by construction new bonds. inert C−C single bonds, especially unstrained cycles, their subsequent is still one most sought‐after challenges In this vein, radical‐mediated provide an approach achieving aim. This minireview outline history homolytic highlights recent advances exploring chemical space functionalization.

Language: Английский

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