Visible Light Induced Photocatalyst‐Free C−X (X=B, C, O, P,S, Se) Bond Formation of Aryl Halides

Advanced Synthesis & Catalysis, Год журнала: 2024, Номер 366(8), С. 1719 - 1737

Опубликована: Фев. 29, 2024

Abstract Aryl halides are one of the most important chemical feedstocks in pharmaceuticals due to its easy accessibility, inexpensiveness, and widely utilized as aryl radical precursors organic synthetic chemistry. Conventionally, stoichiometric reagents such AIBN/n‐Bu 3 SnH were used for generation from halides, suffered requirement toxic initiators, high temperature thus, development simple, mild strategies highly desirable. Recently, visible light mediated received considerable attention, allowing under reaction conditions. The present review described recent breakthroughs advancements photocatalyst‐free C−B/C/O/P/Se/S bond formation halides.

Язык: Английский

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Transition Metal and Photocatalyst Free Arylation via Photoexcitable Electron Donor Acceptor Complexes:Mediation and Catalysis

ChemCatChem, Год журнала: 2024, Номер 16(11)

Опубликована: Янв. 15, 2024

Abstract Visible‐light‐activated organic reactions unlock novel avenues for complex molecular transformations, impossible under standard “thermal” conditions, which makes them powerful tools in the arsenal of synthetic chemistry. However, transition metal‐based or photoredox catalysts are often used to ensure productive absorption visible light, might be not desirable medicinal chemistry and industry due toxicity, low sustainability, high cost most photocatalysts. A more environmentally economically benign approach is based on formation transient electron donor‐acceptor (EDA) complexes between two reagents a reagent an additive, that readily absorb acting as internal photosensitizers. Within EDA complex‐based arylation strategies, chemical transformations mediated by noncovalent interaction molecules, namely electron‐poor aryl halides their equivalents electron‐rich nucleophilic additives. Moreover, besides stoichiometric organocatalysis can achieved certain cases through regeneration donor molecules course reaction. Photoexcitation induces single transfer (SET) process generate radical species step. This Review will focus state‐of‐the‐art strategies utilizing halides, aryldiazonium, diaryliodonium, arylsulfonium arylphosphonium salts reactants, published mainly last five years.

Язык: Английский

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Iodoarene Activation: Take a Leap Forward toward Green and Sustainable Transformations

Chemical Reviews, Год журнала: 2025, Номер unknown

Опубликована: Март 7, 2025

Constructing chemical bonds under green sustainable conditions has drawn attention from environmental and economic perspectives. The dissociation of (hetero)aryl-halide is a crucial step most arylations affording (hetero)arene derivatives. Herein, we summarize the (hetero)aryl halides activation enabling direct (hetero)arylation trapping reagents construction highly functionalized (hetero)arenes benign conditions. strategies for aryl iodides are classified into (a) hypervalent iodoarene followed by functionalization thermal/photochemical conditions, (b) aryl-I bond in presence bases with/without organic catalysts promoters, (c) photoinduced presence/absence organophotocatalysts, (d) electrochemical direct/indirect electrolysis mediated organocatalysts mediators acting as electron shuttles, (e) electrophotochemical redox-active organocatalysts. These modes result exhibiting diverse reactivity formal cations/radicals/anions aryne precursors. coupling these reactive intermediates with leads to facile selective formation C-C C-heteroatom bonds. ecofriendly, inexpensive, functional group-tolerant offer alternatives transition metal-based catalysis.

Язык: Английский

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Visible-Light-Driven Thioesterification of Aryl Halides with Potassium Thiocarboxylates: Transition-Metal Catalyst-Free Incorporation of Sulfur Functionalities into an Aromatic Ring

The Journal of Organic Chemistry, Год журнала: 2022, Номер 87(12), С. 8170 - 8182

Опубликована: Июнь 2, 2022

Reactions of acceptor-substituted aryl iodides and bromides with potassium thiocarboxylates under white light irradiation allow for the preparation S-aryl thioesters including synthetically versatile thioacetates. This transition-metal external photocatalyst-free method features extremely mild reaction conditions compared those used in transition-metal-catalyzed protocols. proceed via initial formation an electron donor-acceptor (EDA) complex ground state, which was supported by UV-vis spectra. Electron paramagnetic resonance (EPR) spin-trapping experiments using phenyl-N-tert-butylnitrone (PBN) have revealed radical nature reaction.

Язык: Английский

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Metal‐Free Visible‐light Mediated C−S Bond Formation

Asian Journal of Organic Chemistry, Год журнала: 2023, Номер 12(8)

Опубликована: Июнь 26, 2023

Abstract The upsurge in interest the development of methodologies for synthesis sulfur‐containing compounds via use visible‐light has been established as a sustainable tool organic chemistry. Particularly, mediated C−S bond formation gained popularity due to its operational simplicity, minimized by‐products, easy handling, mild reaction conditions, etc. Photochemistry not only provides way synthesize complex molecules but also ability overcome many challenges which are difficult attain by conventional thermal pathways. Owing biological importance compounds, present review focused on under metal‐free conditions visible‐light. objective current is bring out unearthing collection regarding photoredox catalysis. For better understanding, categorized according mode reactions viz , difunctionalization alkenes and alkynes, C−H functionalization, radical cyclization. All each sections described with selected examples proper explanation proposed mechanism.

Язык: Английский

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Photocatalyst‐ and Transition‐Metal‐Free Light‐Induced Formation of Carbon‐Chalcogen Bonds

Advanced Synthesis & Catalysis, Год журнала: 2023, Номер 366(2), С. 168 - 182

Опубликована: Дек. 16, 2023

Abstract Photoinduced chemical transformations have become a promising aspect of organic synthesis. This review focuses on the recent advancements in harnessing photoinduced processes for formation carbon‐chalcogen (C−O, C−S, C−Se, and C−Te) bonds under catalyst‐free conditions. These pathways typically involve either radical mechanism or creation electron‐donor‐acceptor (EDA) complexes. The explores intricacies underlying mechanisms, discusses limitations, evaluates applicability various methodologies this field. Notably, photocatalyst transition metal‐free photochemical reactions offer effective alternatives to enhance sustainability research area.

Язык: Английский

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Metal-Free Photocatalyst with Redox Center and Lewis Acid Site for Selective Synthesis of Mono- and Disubstituted Benzimidazoles via Alcohol and Aromatic Diamine Cross-Dehydrocoupling

ACS Sustainable Chemistry & Engineering, Год журнала: 2023, Номер 11(38), С. 14056 - 14067

Опубликована: Сен. 11, 2023

Here we present the first metal- and additive-free bipyridinium-based photocatalyst for selective dehydrocondensation of aromatic diamine with alcohol to mono- disubstituted benzimidazoles under mild conditions by modulating composition solvent. Notably, method is versatile applicable less reactive substrates such as heterocyclic alcohols aliphatic well synthesis quinoxaline pharmaceutically active molecule benzothiazole. In contrast most other photocatalytic systems benzimidazole in which aldehydes o-phenylenediamine are used substrates, replacement shows great advantages due abundant cost-effective nature fermentation products renewable plant-derived materials fact that sole byproduct using environmentally friendly water stoichiometric quantities. Combining redox activity Lewis acidity bipyridinium photocatalyst, benzyl was oxidized benzaldehyde activated singlet oxygen superoxide free radicals, then intermediate were acid sites catalyst reacted produce cross-dehydrocoupling.

Язык: Английский

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Visible Light-Induced Decomposition of Acyl Peroxides Using Isocyanides: Synthesis of Heteroarenes by Radical Cascade Cyclization

The Journal of Organic Chemistry, Год журнала: 2023, Номер 88(9), С. 5431 - 5439

Опубликована: Апрель 24, 2023

Visible light-mediated facile synthesis of heteroarenes, namely, isoquinolines, benzothiazoles, and quinazolines, is demonstrated by employing isocyanides inexpensive acyl peroxides. It shown for the first time that singlet-excited decompose peroxides into aryl/alkyl radicals. The latter attack isocyanides, yielding imidoyl radicals subsequently cyclize to afford heteroarene products. protocol involving radical cascade reactions obviates requirement any external photocatalyst, oxidant, additive, base.

Язык: Английский

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Iron(III)-Catalyzed Regioselective Synthesis of Electron-Rich Benzothiazoles from Aryl Isothiocyanates via C–H Functionalization

The Journal of Organic Chemistry, Год журнала: 2023, Номер 88(7), С. 4458 - 4471

Опубликована: Март 13, 2023

We report herein a direct synthetic route for the preparation of 2-arylbenzothiazoles using aryl isothiocyanates and electron-rich arenes. The involves triflic acid promoted addition arenes to followed by FeCl3-catalyzed C–S bond formation via C–H functionalization. approach provides advantage synthesis benzothiazoles without conventional use aldehyde/carboxylic precursors employing less expensive iron(III) catalyst.

Язык: Английский

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Metal- and base-free, aerobic photoredox catalysis with riboflavin to synthesize 2-substituted benzothiazoles

Organic & Biomolecular Chemistry, Год журнала: 2024, Номер 22(5), С. 1064 - 1072

Опубликована: Янв. 1, 2024

A straightforward and environmentally friendly riboflavin-based photocatalytic approach for the synthesis of 2-substituted benzothiazoles has been described.

Язык: Английский

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