New Redox Strategies in Organic Synthesis by Means of Electrochemistry and Photochemistry

ACS Central Science, Год журнала: 2020, Номер 6(8), С. 1317 - 1340

Опубликована: Июль 16, 2020

As the breadth of radical chemistry grows, new means to promote and regulate single-electron redox activities play increasingly important roles in driving modern synthetic innovation. In this regard, photochemistry electrochemistry-both considered as niche fields for decades-have seen an explosive renewal interest recent years gradually have become a cornerstone organic chemistry. Outlook article, we examine current state-of-the-art areas electrochemistry photochemistry, well nascent area electrophotochemistry. These techniques employ external stimuli activate molecules imbue privileged control reaction progress selectivity that is challenging traditional chemical methods. Thus, they provide alternative entries known reactive intermediates enable distinct strategies were previously unimaginable. Of many hallmarks, electro- are often classified "green" technologies, promoting reactions under mild conditions without necessity potent wasteful oxidants reductants. This reviews most growth these with special emphasis on conceptual advances given rise enhanced accessibility tools trade.

Язык: Английский

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Photons or Electrons? A Critical Comparison of Electrochemistry and Photoredox Catalysis for Organic Synthesis

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 2487 - 2649

Опубликована: Ноя. 9, 2021

Redox processes are at the heart of synthetic methods that rely on either electrochemistry or photoredox catalysis, but how do and catalysis compare? Both approaches provide access to high energy intermediates (e.g., radicals) enable bond formations not constrained by rules ionic 2 electron (e) mechanisms. Instead, they 1e mechanisms capable bypassing electronic steric limitations protecting group requirements, thus enabling chemists disconnect molecules in new different ways. However, while providing similar intermediates, differ several physical chemistry principles. Understanding those differences can be key designing transformations forging disconnections. This review aims highlight these similarities between comparing their underlying principles describing impact electrochemical photochemical methods.

Язык: Английский

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Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 2650 - 2694

Опубликована: Авг. 27, 2021

Geometrical E → Z alkene isomerization is intimately entwined in the historical fabric of organic photochemistry and enjoying a renaissance (Roth et al. Angew. Chem., Int. Ed. Engl. 1989 28, 1193–1207). This consequence fundamental stereochemical importance Z-alkenes, juxtaposed with frustrations thermal reactivity that are rooted microscopic reversibility. Accessing excited state paradigms allow this latter obstacle to be circumnavigated by exploiting subtle differences photophysical behavior substrate product chromophores: provides molecular basis for directionality. While direct irradiation operationally simple, photosensitization via selective energy transfer enables augmentation repertoire include substrates not directly photons. Through sustained innovation, an impressive portfolio tailored small molecule catalysts range triplet energies now widely available facilitate contra-thermodynamic thermo-neutral reactions generate Z-alkene fragments. review intended serve as practical guide covering geometric alkenes enabled catalysis from 2000 2020, logical sequel excellent treatment Dugave Demange (Chem. Rev. 2003 103, 2475–2532). The mechanistic foundations underpinning selectivity discussed together induction models rationales explain counterintuitive directionality these processes which very distinguish product. Implications subsequent stereospecific transformations, application total synthesis, regioselective polyene isomerization, spatiotemporal control pre-existing configuration broader sense discussed.

Язык: Английский

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Energy transfer photocatalysis: exciting modes of reactivity

Chemical Society Reviews, Год журнала: 2024, Номер 53(3), С. 1068 - 1089

Опубликована: Янв. 1, 2024

Leveraging light energy to expose the ‘dark’ reactive states describes whole essence of triplet–triplet transfer. This offers an impressive opportunity conduct a multitude diverse reactions and access sought-after molecular motifs.

Язык: Английский

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Site-Selective Acceptorless Dehydrogenation of Aliphatics Enabled by Organophotoredox/Cobalt Dual Catalysis

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(40), С. 16470 - 16485

Опубликована: Сен. 30, 2021

The value of catalytic dehydrogenation aliphatics (CDA) in organic synthesis has remained largely underexplored. Known homogeneous CDA systems often require the use sacrificial hydrogen acceptors (or oxidants), precious metal catalysts, and harsh reaction conditions, thus limiting most existing methods to non- or low-functionalized alkanes. Here we describe a visible-light-driven, dual-catalyst system consisting inexpensive organophotoredox base-metal catalysts for room-temperature, acceptorless-CDA (Al-CDA). Initiated by photoexited 2-chloroanthraquinone, process involves H atom transfer (HAT) form alkyl radicals, which then react with cobaloxime produce olefins H2. This operationally simple method enables direct readily available chemical feedstocks diversely functionalized olefins. For example, demonstrate, first time, oxidant-free desaturation thioethers amides alkenyl sulfides enamides, respectively. Moreover, system's exceptional site selectivity functional group tolerance are illustrated late-stage 14 biologically relevant molecules pharmaceutical ingredients. Mechanistic studies have revealed dual HAT provided insights into origin reactivity selectivity.

Язык: Английский

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General heterostructure strategy of photothermal materials for scalable solar-heating hydrogen production without the consumption of artificial energy

Nature Communications, Год журнала: 2022, Номер 13(1)

Опубликована: Фев. 9, 2022

Solar-heating catalysis has the potential to realize zero artificial energy consumption, which is restricted by low ambient solar heating temperatures of photothermal materials. Here, we propose concept using heterostructures black materials (such as Bi2Te3) and infrared insulating (Cu) elevate temperatures. Consequently, heterostructure Bi2Te3 Cu (Bi2Te3/Cu) increases 1 sun-heating temperature from 93 °C 317 achieving synergy 89% absorption 5% radiation. This strategy applicable for various raise Ti2O3, Cu2Se, Cu2S 295 °C, 271 248 respectively. The Bi2Te3/Cu-based device able heat CuOx/ZnO/Al2O3 nanosheets 305 under sun irradiation, this system shows a sun-driven hydrogen production rate 310 mmol g-1 h-1 methanol water, at least 6 times greater than that all solar-driven systems date, with 30.1% solar-to-hydrogen efficiency 20-day operating stability. Furthermore, enlarged m2 generate 23.27 m3/day outdoor sunlight irradiation in spring, revealing its industrial manufacture.

Язык: Английский

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Deracemization through photochemical E / Z isomerization of enamines

Science, Год журнала: 2022, Номер 375(6583), С. 869 - 874

Опубликована: Фев. 24, 2022

Catalytic deracemization of α-branched aldehydes is a direct strategy to construct enantiopure α-tertiary carbonyls, which are essential pharmaceutical applications. Here, we report photochemical E/Z isomerization for the by using simple aminocatalysts and readily available photosensitizers. A variety racemic could be directly transformed into either enantiomer with high selectivity. Rapid photodynamic highly stereospecific iminium/enamine tautomerization two key factors that underlie enantioenrichment. This study presents distinctive externally tuning enamine catalysis.

Язык: Английский

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Synthesis of Cyclopropenols Enabled by Visible‐Light‐Induced Organocatalyzed [2+1] Cyclization

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(10)

Опубликована: Янв. 7, 2022

Although the synthesis of common cyclopropenes has been well studied, access to cyclopropenols is rather limited. Herein, we report first α-trifluoromethylated via 2+1 cycloaddition reactions between alkynes and trifluoroacylsilanes, enabled by visible-light-induced organocatalysis. The novel ambiphilic donor-acceptor carbenes derived from trifluoroacetylsilanes reacted efficiently with both activated non-activated alkynes. reaction features simple operation, mild conditions, broad substrate scope good functional group tolerance. synthetic potential highlighted gram-scale cyclopropanols through combination cyclization high diastereoselective hydrogenation in one pot.

Язык: Английский

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Light-enabled deracemization of cyclopropanes by Al-salen photocatalysis

Nature, Год журнала: 2023, Номер 621(7980), С. 753 - 759

Опубликована: Авг. 23, 2023

Privileged chiral catalysts-those that share common structural features and are enantioselective across a range of reactions-continue to transform the chemical-research landscape1. In recent years, new reactivity modes have been achieved through excited-state catalysis, processes activated by light, but it is unclear if selectivity ground-state privileged catalysts can be matched. Although interception photogenerated intermediates cycles has partially addressed this challenge2, single, photocatalysts simultaneously regulate conspicuously scarce3. So far, precision donor-acceptor recognition motifs remain crucial in photocatalyst design4. Here we show Al-salen complexes, which well-defined photophysical properties, used for efficient photochemical deracemization5 cyclopropyl ketones (up 98:2 enantiomeric ratio (e.r.)). Irradiation at λ = 400 nm (violet light) augments commercial catalyst enable enantioselectivity regulated simultaneously. This circumvents need tailored catalyst-substrate motifs. It predicted study will stimulate re-evaluation many venerable (ground-state) processes, ultimately leading identification candidates may considered 'privileged' both models.

Язык: Английский

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The impact of UV light on synthetic photochemistry and photocatalysis

Nature Chemistry, Год журнала: 2024, Номер 16(5), С. 684 - 692

Опубликована: Март 1, 2024

Язык: Английский

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