Strategies to Generate Nitrogen-centered Radicals That May Rely on Photoredox Catalysis: Development in Reaction Methodology and Applications in Organic Synthesis

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 2353 - 2428

Опубликована: Окт. 8, 2021

For more than 70 years, nitrogen-centered radicals have been recognized as potent synthetic intermediates. This review is a survey designed for use by chemists engaged in target-oriented synthesis. summarizes the recent paradigm shift access to and application of N-centered enabled visible-light photocatalysis. broadens streamlines approaches many small molecules because photocatalysis conditions are mild. Explicit attention paid innovative advances N–X bonds radical precursors, where X = Cl, N, S, O, H. clarity, key mechanistic data noted, available. Synthetic applications limitations summarized illuminate tremendous utility photocatalytically generated radicals.

Язык: Английский

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Microfluidic electrochemistry for single-electron transfer redox-neutral reactions

Science, Год журнала: 2020, Номер 368(6497), С. 1352 - 1357

Опубликована: Июнь 18, 2020

Electrochemistry offers opportunities to promote single-electron transfer (SET) redox-neutral chemistries similar those recently discovered using visible-light photocatalysis but without the use of an expensive photocatalyst. Herein, we introduce a microfluidic electrochemistry (μRN-eChem) platform that has broad applicability SET chemistry, including radical-radical cross-coupling, Minisci-type reactions, and nickel-catalyzed C(sp2)-O cross-coupling. The cathode anode simultaneously generate corresponding reactive intermediates, selective transformation is facilitated by rapid molecular diffusion across channel outpaces decomposition intermediates. μRN-eChem was shown enable two-step gram-scale electrosynthesis nematic liquid crystal compound, demonstrating its practicality.

Язык: Английский

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Pyridinium Salts as Redox‐Active Functional Group Transfer Reagents

Angewandte Chemie International Edition, Год журнала: 2019, Номер 59(24), С. 9264 - 9280

Опубликована: Окт. 10, 2019

Abstract In this Review, we highlight recent advances in the understanding and design of N‐functionalized pyridinium scaffolds as redox‐active, single‐electron, functional group transfer reagents. We provide a selection representative methods that demonstrate reactivity fundamental emerging field. The these reagents can be divided into two divergent pathways: homolytic fragmentation to liberate N‐bound substituent corresponding radical or an alternative heterolytic liberates N‐centered radical. A short description elementary steps involved induced by single‐electron is also critically discussed guide readers towards processes thought occur under conditions.

Язык: Английский

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Enantioselective Radical Reactions Using Chiral Catalysts

Chemical Reviews, Год журнала: 2022, Номер 122(6), С. 5842 - 5976

Опубликована: Янв. 24, 2022

Benefiting from the impressive increase in fundamental knowledge, last 20 years have shown a continuous burst of new ideas and consequently plethora catalytic methods for enantioselective radical reactions. This review aims to provide complete survey progress achieved over this latter period. The first part focuses on use chiral organocatalysts, these include catalysts covalently linked substrate those that interact with by weaker interactions like hydrogen bonds. second is devoted transition-metal redox catalysis which organized according increasing atomic number first-row transition metals (Ti, Cr, Fe, Mn, Co, Ni, Cu). Bioinspired manganese- iron-mediated hydroxylations oxidations are also discussed. A specific section dedicated reactivity Ru, Rh, Ir complexes as Lewis acids special focus at metal. Absorption photons result different events such energy transfer, single-electron hydrogen-atom transfer facilitating formation radicals. Organocatalysis has been successfully combined photocatalysts, opened pathways enlarging precursors available. merger photocatalysis organo- or metalla-photocatalysis brought novelty allowed discovery large original transformations. enzyme-catalyzed reactions involving intermediates largely benefit visible-light irradiation included review. provides comprehensive inventory goal detailing reaction mechanisms involved transformations any nonspecialist could find their own creativity invent yet unknown applications.

Язык: Английский

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Scalable Photoelectrochemical Dehydrogenative Cross‐Coupling of Heteroarenes with Aliphatic C−H Bonds

Angewandte Chemie International Edition, Год журнала: 2020, Номер 59(34), С. 14275 - 14280

Опубликована: Июнь 3, 2020

Heteroarenes are structural motifs found in many bioactive compounds and functional materials. Dehydrogenative cross-coupling of heteroarenes with aliphatic C-H bonds provides straightforward access to functionalized from readily available Established methods employ stoichiometric chemical oxidants under conditions heating or light irradiation. By merging electrochemistry photochemistry, we have achieved efficient photoelectrochemical dehydrogenative C(sp3 )-H donors through H2 evolution, without the addition metal catalysts oxidants. Mechanistically, donor is converted a nucleophilic carbon radical H-atom transfer chlorine atom, which produced by irradiation anodically generated Cl2 Cl- . The then undergoes substitution heteroarene afford alkylated products.

Язык: Английский

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A Perspective on Late-Stage Aromatic C–H Bond Functionalization

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(6), С. 2399 - 2414

Опубликована: Янв. 27, 2022

Late-stage functionalization of C-H bonds (C-H LSF) can provide a straightforward approach to the efficient synthesis functionalized complex molecules. However, LSF is challenging because bond must be in presence various other functional groups. In this Perspective, we evaluate aromatic on basis four criteria─reactivity, chemoselectivity, site-selectivity, and substrate scope─and our own views current challenges as well promising strategies areas growth going forward.

Язык: Английский

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Ligand‐to‐Metal Charge Transfer (LMCT) Photochemistry at 3d‐Metal Complexes: An Emerging Tool for Sustainable Organic Synthesis

ChemCatChem, Год журнала: 2022, Номер 14(19)

Опубликована: Авг. 11, 2022

Abstract Despite the rich photochemistry of 3d‐metal complexes, utilization excited‐state reactivity these compounds in organic synthesis has been historically overlooked. The advent photoredox catalysis changed perception synthetic chemists towards photochemistry, and nowadays potential photoinduced, outer‐sphere single‐electron transfer events is widely recognized. More recently, an emerging new mode photoactivation taken spotlight, based on inner‐sphere triggered by population ligand‐to‐metal charge‐transfer (LMCT) excited states. Contrarily to photoredox, LMCT‐activation does not rely matching redox potentials, offers unique profiles particularly well suited Earth‐abundant metal complexes. Those appealing features are propelling development methods using this blueprint generate highly reactive open‐shell species under mild conditions. aim contribution provide a didactical tool for comprehension concept facilitate methodologies achieve sustainable chemical transformations.

Язык: Английский

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Electrophotocatalytic Decarboxylative C−H Functionalization of Heteroarenes

Angewandte Chemie International Edition, Год журнала: 2020, Номер 59(26), С. 10626 - 10632

Опубликована: Март 30, 2020

Abstract Decarboxylative C−H functionalization reactions are highly attractive methods for forging carbon–carbon bonds considering their inherent step‐ and atom‐economical features the pervasiveness of carboxylic acids bonds. An ideal approach to achieve these dehydrogenative transformations is through hydrogen evolution without using any chemical oxidants. However, effective couplings by decarboxylative bond formation with proton reduction remain an unsolved challenge. Herein, we report electrophotocatalytic that merges organic electrochemistry photocatalysis efficient direct alkylation carbamoylation heteroaromatic compounds evolution. This method, which combines high efficiency selectivity in promoting decarboxylation superiority effecting reduction, enables coupling a wide range bases variety oxamic acids. Advantageously, this method scalable decagram amounts, applicable late‐stage drug molecules.

Язык: Английский

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Radical C(sp3)–H functionalization and cross-coupling reactions

Nature Reviews Chemistry, Год журнала: 2022, Номер 6(6), С. 405 - 427

Опубликована: Май 17, 2022

Язык: Английский

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Electrophotocatalytic C–H Functionalization of Ethers with High Regioselectivity

Journal of the American Chemical Society, Год журнала: 2020, Номер 142(4), С. 1698 - 1703

Опубликована: Янв. 6, 2020

The highly regioselective electrophotocatalytic C–H functionalization of ethers is described. These reactions are catalyzed by a trisaminocyclopropenium (TAC) ion at mild electrochemical potential with visible light irradiation. Ethers undergo oxidant-free coupling isoquinolines, alkenes, alkynes, pyrazoles, and purines typically high regioselectivity for the less-hindered α-position. reaction proposed to operate via hydrogen atom transfer (HAT) from substrate photoexcited TAC radical dication, thus demonstrating new reactivity mode this electrophotocatalyst.

Язык: Английский

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