Synthetic Methods Driven by the Photoactivity of Electron Donor–Acceptor Complexes

Journal of the American Chemical Society, Год журнала: 2020, Номер 142(12), С. 5461 - 5476

Опубликована: Март 5, 2020

The association of an electron-rich substrate with electron-accepting molecule can generate a new molecular aggregate in the ground state, called electron donor-acceptor (EDA) complex. Even when two precursors do not absorb visible light, resulting EDA complex often does. In 1952, Mulliken proposed quantum-mechanical theory to rationalize formation such colored complexes. However, and besides few pioneering studies 20th century, it is only past years that photochemistry has been recognized as powerful strategy for expanding potential visible-light-driven radical synthetic chemistry. Here, we explain why this photochemical approach was overlooked so long. We critically discuss historical context, scientific reasons, serendipitous observations, landmark discoveries were essential progress field. also outline future directions identify key advances are needed fully exploit photochemistry.

Язык: Английский

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Radical Carboxylative Cyclizations and Carboxylations with CO₂

Accounts of Chemical Research, Год журнала: 2021, Номер 54(10), С. 2518 - 2531

Опубликована: Май 6, 2021

ConspectusCarbon dioxide (CO2) is not only a greenhouse gas and common waste product but also an inexpensive, readily available, renewable carbon resource. It important one-carbon (C1) building block in organic synthesis for the construction of valuable compounds. However, its utilization challenging owing to thermodynamic stability kinetic inertness. Although significant progress has been achieved, many limitations remain this field with regard substrate scope, reaction system, activation strategies.Since 2015, our group focused on CO2 synthesis. We are interested vast possibilities radical chemistry, although high reactivity radicals presents challenges controlling selectivity. hope develop highly useful transformations involving by achieving balance selectivity under mild conditions. Over past 6 years, we along other experts have disclosed radical-type carboxylative cyclizations carboxylations using CO2.We initiated research realizing Cu-catalyzed oxytrifluoromethylation allylamines heteroaryl methylamines generate 2-oxazolidones various precursors. Apart from Cu catalysis, visible-light photoredox catalysis powerful method achieve efficient cyclization. In these cases, single-electron-oxidation-promoted C–O bond formation between benzylic carbamates key step.Since carboxylic acids exist widely natural products bioactive drugs serve as bulk chemicals industry, realized further visible-light-promoted construct such chemicals. achieved selective umpolung imines, enamides, tetraalkylammonium salts, oxime esters successive single-electron-transfer (SSET) reduction. Using strategy, dearomative arylcarboxylation indoles CO2. addition incorporation 1 equiv per substrate, recently developed photoredox-catalyzed dicarboxylation alkenes, allenes, (hetero)arenes via SSET reduction, which allows two molecules into compounds diacids polymer precursors.In two-electron CO2, sought new strategies realize single-electron Inspired hypothetical electron-transfer mechanism iron–sulfur proteins, visible-light-driven thiocarboxylation alkenes catalytic iron salts promoters. The in-situ-generated Fe/S complexes likely able reduce anion, could react give stabilized radical. Moreover, charge-transfer complex (CTC) thiolate acrylate/styrene hydrocarboxylation generation or alkene anion. On basis novel CTC, organocatalytic Hantzsch ester effective reductant.

Язык: Английский

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A General Organocatalytic System for Electron Donor–Acceptor Complex Photoactivation and Its Use in Radical Processes

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(31), С. 12304 - 12314

Опубликована: Июль 28, 2021

We report herein a modular class of organic catalysts that, acting as donors, can readily form photoactive electron donor-acceptor (EDA) complexes with variety radical precursors. Excitation visible light generates open-shell intermediates under mild conditions, including nonstabilized carbon radicals and nitrogen-centered radicals. The nature the commercially available xanthogenate dithiocarbamate anion organocatalysts offers versatile EDA complex catalytic platform for developing mechanistically distinct reactions, encompassing redox-neutral net-reductive processes. Mechanistic investigations, by means quantum yield determination, established that closed cycle is operational all developed processes, highlighting ability to turn over iteratively drive every cycle. also demonstrate how catalysts' stability method's high functional group tolerance could be advantageous direct functionalization abundant groups, aliphatic carboxylic acids amines, applications in late-stage elaboration biorelevant compounds enantioselective catalysis.

Язык: Английский

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Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

Beilstein Journal of Organic Chemistry, Год журнала: 2021, Номер 17, С. 771 - 799

Опубликована: Апрель 6, 2021

The reversible, weak ground-state aggregate formed by dipole–dipole interactions between an electron donor and acceptor is referred to as electron-donor–acceptor (EDA) complex. Generally, upon light irradiation, the EDA complex turns into excited state, causing transfer give radicals initiate subsequent reactions. Besides external energy source, reactions involving participation of complexes are mild, obviating transition metal catalysts or photosensitizers in majority cases line with theme green chemistry. This review discusses synthetic concerned well mechanisms that have been shown over past five years.

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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Sulfonium Salts as Acceptors in Electron Donor‐Acceptor Complexes

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(29)

Опубликована: Март 24, 2023

Abstract The photoactivation of electron donor‐acceptor complexes has emerged as a sustainable, selective and versatile strategy for the generation radical species. Electron (EDA) complexation, however, imposes electronic constraints on donor acceptor components this can limit range radicals that be generated using approach. New EDA complexation strategies exploiting sulfonium salts allow to from native functionality. For example, aryl salts, formed by activation arenes, serve in due their electron‐deficient nature. This “sulfonium tag” approach relaxes parent substrate dramatically expands complexation. In review, these new applications will introduced areas chemical space rendered accessible through innovation highlighted.

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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Visible-Light-Driven C4-Selective Alkylation of Pyridinium Derivatives with Alkyl Bromides

Journal of the American Chemical Society, Год журнала: 2020, Номер 142(26), С. 11370 - 11375

Опубликована: Июнь 12, 2020

Reported herein is a general strategy for the photochemical cross-coupling between N-amidopyridinium salts and various alkyl bromides under photocatalyst-free conditions, granting facile access to C4-alkylated pyridines. This approach exploits intriguing activity of electron donor-acceptor (EDA) complexes bromide, which provides photoactive handle capable generating silyl radicals driving alkylation process. The robustness this protocol was further demonstrated by late-stage functionalization complex compounds mild metal-free conditions.

Язык: Английский

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Design and Implementation of a Catalytic Electron Donor–Acceptor Complex Platform for Radical Trifluoromethylation and Alkylation

ACS Catalysis, Год журнала: 2020, Номер 10(21), С. 12636 - 12641

Опубликована: Окт. 16, 2020

Electron donor–acceptor (EDA) complexes can controllably generate radicals under mild conditions through selective photoexcitation events. However, unproductive reactivity from fast deactivation of the photoexcited back electron transfer has slowed development EDA in synthetic methodology. Here, we disclose study derived 2-methoxynaphthalene donor and acylated ethyl isonicotinate N-oxide acceptor that undergo a N–O bond fragmentation event upon photoexcitation. This reaction design not only overcomes limitations but also enables regeneration species, representing rare example photochemistry catalytic regime. The utility is demonstrated visible light-driven radical trifluoromethylation Minisci alkylation reactions. scalability complex-promoted evidenced by successful multigram-scale methyl N-Boc pyrrole-2-carboxylate continuous flow manifold.

Язык: Английский

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Recent Methodologies That Exploit Oxidative Addition of C–N Bonds to Transition Metals

ACS Catalysis, Год журнала: 2020, Номер 10(21), С. 12738 - 12759

Опубликована: Окт. 19, 2020

The activation of σ-bonds by transition metals underpins a wide range methods for the synthesis complex molecules. Within this context, C–N bond has emerged recently as powerful strategy preparation or utilization nitrogen-containing compounds, due to prevalence bonds in organic compounds. A key challenge area is that most are relatively inert, and makes their difficult task. Since turn millennium number published articles regarding grown exponentially, providing important improvements methodologies such transformations. Indeed, several distinct strategies have been developed achieve activation. common exploited either strain release quaternization nitrogen center, while other state-of-the-art strategies, oxidative addition neutral use directing groups, also appeared. Despite considerable progress, deeper insight into mechanisms atom economy still required field advance. In Perspective we give an overview advances catalytic where achieved metals.

Язык: Английский

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