Applications of Halogen-Atom Transfer (XAT) for the Generation of Carbon Radicals in Synthetic Photochemistry and Photocatalysis

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 2292 - 2352

Опубликована: Дек. 9, 2021

The halogen-atom transfer (XAT) is one of the most important and applied processes for generation carbon radicals in synthetic chemistry. In this review, we summarize highlight aspects associated with XAT impact it has had on photochemistry photocatalysis. organization material starts analysis mechanistic then follows a subdivision based nature reagents used halogen abstraction. This review aims to provide general overview fundamental concepts main agents involved objective offering tool understand facilitate development new radical strategies.

Язык: Английский

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Photocatalytic Late-Stage C–H Functionalization

Chemical Reviews, Год журнала: 2023, Номер 123(8), С. 4237 - 4352

Опубликована: Янв. 24, 2023

The emergence of modern photocatalysis, characterized by mildness and selectivity, has significantly spurred innovative late-stage C–H functionalization approaches that make use low energy photons as a controllable source. Compared to traditional strategies, photocatalysis paves the way toward complementary and/or previously unattainable regio- chemoselectivities. Merging compelling benefits with workflow offers potentially unmatched arsenal tackle drug development campaigns beyond. This Review highlights photocatalytic strategies small-molecule drugs, agrochemicals, natural products, classified according targeted bond newly formed one. Emphasis is devoted identifying, describing, comparing main mechanistic scenarios. draws critical comparison between established ionic chemistry photocatalyzed radical-based manifolds. aims establish current state-of-the-art illustrate key unsolved challenges be addressed in future. authors aim introduce general readership functionalization, specialist practitioners evaluation methodologies, potential for improvement, future uncharted directions.

Язык: Английский

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Visible‐Light‐Induced 1,3‐Aminopyridylation of [1.1.1]Propellane with N‐Aminopyridinium Salts

Angewandte Chemie International Edition, Год журнала: 2021, Номер 60(14), С. 7873 - 7879

Опубликована: Янв. 7, 2021

Through the formation of an electron donor-acceptor (EDA) complex, strain-release aminopyridylation [1.1.1]propellane with N-aminopyridinium salts as bifunctional reagents enabled direct installation amino and pyridyl groups onto bicyclo[1.1.1]pentane (BCP) frameworks in absence external photocatalyst. The robustness this method to synthesize 1,3-aminopyridylated BCPs under mild metal-free conditions is highlighted by late-stage modification structurally complex biorelevant molecules. Moreover, strategy was extended P-centered CF3 radicals for unprecedented incorporation such functional pyridine across BCP core a three-component coupling. This practical lays foundation straightforward construction new valuable C4-pyridine-functionalized chemical entities, thus significantly expanding range accessibility BCP-type bioisosteres applications drug discovery.

Язык: Английский

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Site-Selective Direct C–H Pyridylation of Unactivated Alkanes by Triplet Excited Anthraquinone

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(7), С. 3003 - 3012

Опубликована: Фев. 8, 2021

Site-selective C-H functionalization in chemical feedstocks is a challenging and useful reaction the broad field of research. Here, we report modular photochemical platform for site-selective pyridylation unactivated hydrocarbons via unique synergistic effects triplet excited anthraquinone an amidyl radical-based reverse hydrogen atom transfer (RHAT) agent. The selective tertiary secondary C(sp3)-H bonds abundant was achieved by employing various N-aminopyridinium salts highly fashion, thus providing new catalytic system direct construction high-value-added compounds under ambient conditions. Moreover, this operationally simple protocol applicable to variety linear-, branched-, cyclo-alkanes more complex molecules with high degrees site selectivity visible-light conditions, which provides rapid straightforward access versatile synthons upgrading mild, metal-free

Язык: Английский

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A general electron donor–acceptor complex for photoactivation of arenes via thianthrenation

Chemical Science, Год журнала: 2022, Номер 13(19), С. 5659 - 5666

Опубликована: Янв. 1, 2022

General photoactivation of EDA complexes between arylsulfonium salts and 1,4-diazabicyclo[2.2.2]octane was discovered. This practical mode enables the generation aryl radicals for C–H functionalization arenes.

Язык: Английский

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Late-Stage C–H Functionalization of Azines

Chemical Reviews, Год журнала: 2023, Номер 123(12), С. 7655 - 7691

Опубликована: Май 3, 2023

Azines, such as pyridines, quinolines, pyrimidines, and pyridazines, are widespread components of pharmaceuticals. Their occurrence derives from a suite physiochemical properties that match key criteria in drug design is tunable by varying their substituents. Developments synthetic chemistry, therefore, directly impact these efforts, methods can install various groups azine C–H bonds particularly valuable. Furthermore, there growing interest late-stage functionalization (LSF) reactions focus on advanced candidate compounds often complex structures with multiple heterocycles, functional groups, reactive sites. Because factors electron-deficient nature the effects Lewis basic N atom, distinct arene counterparts, application LSF contexts difficult. However, have been many significant advances reactions, this review will describe progress, much which has occurred over past decade. It possible to categorize radical addition processes, metal-catalyzed activation transformations occurring via dearomatized intermediates. Substantial variation reaction within each category indicates both rich reactivity heterocycles creativity approaches involved.

Язык: Английский

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N-Functionalized Pyridinium Salts: A New Chapter for Site-Selective Pyridine C–H Functionalization via Radical-Based Processes under Visible Light Irradiation

Accounts of Chemical Research, Год журнала: 2022, Номер 55(20), С. 3043 - 3056

Опубликована: Сен. 27, 2022

ConspectusThe radical-mediated C–H functionalization of pyridines has attracted considerable attention as a powerful tool in synthetic chemistry for the direct bonds pyridine scaffold. Classically, methods functionalized often involve Minisci-type reactions under strongly acidic conditions. However, site-selective unbiased systems been long-standing challenge because scaffold contains multiple competing reaction sites (C2 vs C4) to intercept free radicals. Therefore, prefunctionalization is required avoid issues observed with formation mixture regioisomers and overalkylated side products.Recently, N-functionalized pyridinium salts have attracting organic promising radical precursors surrogates. The notable advantage lies their ability enhance reactivity selectivity synthetically useful acid-free This approach enables exquisite regiocontrol nonclassical at C2 C4 positions mild conditions, which are suitable late-stage bioactive molecules greater complexity diversity. Over past five years, variety fascinating applications developed using various types visible light In addition, new platform alkene difunctionalization appropriately designed N-substituted bifunctional reagents reported, offering an innovative assembly process complex architectures. Intriguingly, strategies involving light-absorbing electron donor–acceptor (EDA) complexes between electron-rich donors further open up photocatalyst-free Furthermore, we enantioselective afford enantioenriched bearing through single-electron N-heterocyclic carbene (NHC) catalysis.Herein, provide broad overview our recent contributions development summarize cornerstones that successfully employ these major advances field systematically categorized on basis pyridines' N-substituent, N–X (X = O, N, C, SO2CF3), its patterns. identification activation modes mechanistic aspects discussed by providing representative each paradigm. We hope this Account will inspire interest continued innovation exploration transformations.

Язык: Английский

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Progress in Photoinduced Radical Reactions using Electron Donor‐Acceptor Complexes

Asian Journal of Organic Chemistry, Год журнала: 2021, Номер 10(4), С. 711 - 748

Опубликована: Фев. 11, 2021

Abstract Photocatalyzed organic synthesis transformation is a remarkable green synthetic strategy because of the advantages operational simplicity, high chemoselectivities, cheap, and environmental benignancy, along with extensive applications in fields organic, pharmaceutical functional material chemistry. Generally, photoredox catalysts or photosensitizers are necessary for generation their excited states to perform successive oxidative reductive reactions through single electron transfer (SET) energy (ET) process. Furthermore, exploration colored donor‐acceptor (EDA) complex charge (CT) between an electron‐rich electron‐poor substrate provides chance deliver intermediate under irradiation light, resulting formation radical activate species induce various reactions. These were performed without need any external photocatalysts mild reaction conditions. Herein, this review focuses on recent progress photoinduced addition reactions, borylations, radical‐radical cross‐coupling degradation cascade cyclization via EDA complexes. We highlight these novel methodologies applications, as well mechanisms. This will help provide references medicinal chemists who charmed by photochemical transformations based

Язык: Английский

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Recent Advances in Electron Donor‐Acceptor (EDA)‐Complex Reactions involving Quaternary Pyridinium Derivatives

Advanced Synthesis & Catalysis, Год журнала: 2023, Номер 365(10), С. 1538 - 1564

Опубликована: Март 6, 2023

Abstract Quaternary pyridinium compounds are valuable intermediates in organic synthesis, which have gained immense popularity the synthetic community. The application of transition metal or photoredox catalysis transforming quaternary into various C−C and C−X bonds is well established. A majority these methods require high temperatures, expansive catalysts, delicate conditions for successful execution. On other hand, use metal‐free photocatalysis‐free strategies constructing using derivatives has been sought‐after. In this context, electron‐donor‐acceptor (EDA)‐complex reactions emerged as a state‐of‐the‐art methodology, do not any photocatalyst their EDA‐complex photochemistry takes advantage electron‐acceptor ability derivatives, can quickly generate radical precursor via deaminative process. These newly generated useful several transformations. We hereby, review, discuss an area major progress mediated involving with mechanism, substrate scope, limitations. magnified image

Язык: Английский

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Energy-transfer-induced [3+2] cycloadditions of N–N pyridinium ylides

Nature Chemistry, Год журнала: 2023, Номер 15(8), С. 1091 - 1099

Опубликована: Июнь 26, 2023

Язык: Английский

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