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

Chemical Reviews, Год журнала: 2020, Номер 121(1), С. 506 - 561

Опубликована: Май 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.

Язык: Английский

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

Accounts of Chemical Research, Год журнала: 2020, Номер 53(5), С. 1066 - 1083

Опубликована: Апрель 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.

Язык: Английский

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Electrochemical Oxidation Induced Selective C–C Bond Cleavage

Chemical Reviews, Год журнала: 2020, Номер 121(1), С. 485 - 505

Опубликована: Окт. 5, 2020

Selective C–C bond cleavage under mild conditions can serve as a valuable tool for organic syntheses and macromolecular degradation. However, the conventional chemical methods have largely involved use of noble transition-metal catalysts well stoichiometric perhaps environmentally unfriendly oxidants, compromising overall sustainable nature transformation chemistry. In this regard, electrochemical has been identified scalable strategy that employs electricity to replace byproduct-generating reagents. To date, progress made in area mainly relied on Kolbe electrolysis related processes. Encouragingly, more examples bonds via other maneuvers recently developed. This review provides an overview most recent significant developments electrochemically oxidative selective cleavage, with emphasis both synthetic outcomes reaction mechanisms, it showcases innate advantages exciting potentials synthesis.

Язык: Английский

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Alkoxy Radicals See the Light: New Paradigms of Photochemical Synthesis

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 2429 - 2486

Опубликована: Окт. 6, 2021

Alkoxy radicals are highly reactive species that have long been recognized as versatile intermediates in organic synthesis. However, their development has impeded due to a lack of convenient methods for generation. Thanks advances photoredox catalysis, enabling facile access alkoxy from bench-stable precursors and free alcohols under mild conditions, research interest this field renewed. This review comprehensively summarizes the recent progress radical-mediated transformations visible light irradiation. Elementary steps radical generation either or central reaction development; thus, each section is categorized discussed accordingly. Throughout review, we focused on different mechanisms well impact synthetic utilizations. Notably, catalytic abundant still early stage, providing intriguing opportunities exploit diverse paradigms.

Язык: Английский

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Radical-Mediated Remote Functional Group Migration

Accounts of Chemical Research, Год журнала: 2020, Номер 53(8), С. 1620 - 1636

Опубликована: Июль 24, 2020

ConspectusAlkenes are ubiquitous in natural products and extensively used as synthetic feedstocks multiple fields including organic synthesis, medicinal chemistry, materials science. Radical-mediated difunctionalization of alkenes provides a powerful tactic for alkene utilization. Despite the considerable progress made past several decades, state-of-the-art methods highly dependent upon activated which proximal group with π-electron system (e.g., aryl, carbonyl, heteroatom) is requisite to stabilize nascent alkyl radical intermediate via p−π conjugation or p orbitals heteroatom. In contrast, transformation unactivated alkenes, such aliphatic remains challenging.To overcome this obstacle, we have recently disclosed strategy intramolecular distal functional migration (FGM), has been efficiently applied alkenes. A portfolio groups, cyano, heteroaryl, oximino, formyl, alkynyl showcase excellent migratory aptitude. Mechanistically, after addition an extrinsic alkene, newly formed active rapidly captured by generate cyclic intermediate. Subsequent cleavage C–C bond leads functionalized product through FGM process. Based on FGM, set elusive difunctionalizations accomplished (Part A).Alongside research, upgraded efficient strategy, "dock-migration," created intermolecular diversity sulfone-based dual-function reagents developed. The initiated docking reagent followed group. Compared original protocol, scope significantly extended from strategically placed tertiary alcohol-substituted general Both well tolerated. By approach, radical-mediated fluoroalkylheteroarylation, fluoroalkylalkynylation, alkylation achieved B).Direct elaboration C–H bonds into targeted groups represents one most ideal straightforward molecular functionalization. proves be ingenious tool functionalization remote C(sp3)–H bonds. process, accomplished: (a) heteroarylation cyanation unprotected alcohols cascade alkoxy radical-enabled hydrogen atom transfer (HAT) cyano) migration, (b) vinylation propargylic consecutive alkenyl radical-promoted HAT process subsequent C).

Язык: Английский

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

Chemical Reviews, Год журнала: 2020, Номер 121(1), С. 264 - 299

Опубликована: Сен. 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.

Язык: Английский

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Nitrogen-Centered Radicals in Functionalization of sp² Systems: Generation, Reactivity, and Applications in Synthesis

Chemical Reviews, Год журнала: 2022, Номер 122(9), С. 8181 - 8260

Опубликована: Март 14, 2022

The chemistry of nitrogen-centered radicals (NCRs) has plentiful applications in organic synthesis, and they continue to expand as our understanding these reactive species increases. utility intermediates is demonstrated the recent advances C–H amination (di)amination alkenes. Synthesis previously challenging structures can be achieved by efficient functionalization sp2 moieties without prefunctionalization, allowing for faster more streamlined synthesis. This Review addresses generation, reactivity, application NCRs, including, but not limited to, iminyl, aminyl, amidyl, aminium species. Contributions from early discovery up most examples have been highlighted, covering radical initiation, thermolysis, photolysis, and, recently, photoredox catalysis. Radical-mediated intermolecular (hetero)arenes occur with a variety complex amine precursors, generating aniline derivatives, an important class drug development. Functionalization olefins achievable high anti-Markovnikov regioselectivity allows access difunctionalized when intermediate carbon are trapped. Additionally, reactivity NCRs harnessed rapid construction N-heterocycles such pyrrolidines, phenanthridines, quinoxalines, quinazolinones.

Язык: Английский

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Selective Carbon–Carbon Bond Cleavage of Cyclopropanols

Chemical Reviews, Год журнала: 2020, Номер 121(1), С. 3 - 79

Опубликована: Окт. 21, 2020

The carbon–carbon (C–C) bond cleavage of cyclopropanols is a wide area research with much current activity. This review highlights new developments in this over the past two decades. A summary made three main reactivity modes, namely, homoenolate chemistry, β-keto radical and acid-catalyzed ring-opening, as well all other methods for C–C functionalization cyclopropanols, including base-mediated metal-catalyzed insertions eliminations, oxidative fragmentation using hypervalent iodine reagents, reactions donor–acceptor pericylic reactions. Emphasis placed on synthetic utility related derivatives, which have emerged unique three-carbon synthons.

Язык: Английский

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Radical-mediated rearrangements: past, present, and future

Chemical Society Reviews, Год журнала: 2021, Номер 50(20), С. 11577 - 11613

Опубликована: Янв. 1, 2021

This Review summarizes the past to present achievements in radical-mediated rearrangements, and brings up prospects that may inspire colleagues develop more useful synthetic tools based on radical rearrangements.

Язык: Английский

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Upcycling to Sustainably Reuse Plastics

Advanced Materials, Год журнала: 2021, Номер 34(25)

Опубликована: Июль 8, 2021

Plastics are now indispensable in daily lives. However, the pollution from plastics is also increasingly becoming a serious environmental issue. Recent years have seen more sustainable approaches and technologies, commonly known as upcycling, to transform into value-added materials chemical feedstocks. In this review, latest research on upcycling presented, with greater focus use of renewable energy well selective methods repurpose synthetic polymers. First, thermal briefly introduced, including redeployment for construction uses, 3D printing precursors, lightweight materials. Then, some novel strategies deconstruct condensation polymers monomers repolymerization or introduce vulnerable linkers make degradable discussed. Subsequently, review will explore breakthroughs by heterogeneous homogeneous photocatalysis, electrocatalysis, which versatile fine chemicals while simultaneously mitigating global climate change. addition, biotechnological advances discovery engineering microbes that can decompose presented. Finally, current challenges outlook future discussed stimulate cooperation field.

Язык: Английский

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