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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Sequential C–F bond functionalizations of trifluoroacetamides and acetates via spin-center shifts

Science, Год журнала: 2021, Номер 371(6535), С. 1232 - 1240

Опубликована: Март 5, 2021

Defluorinative functionalization of readily accessible trifluoromethyl groups constitutes an economical route to partially fluorinated molecules. However, the controllable replacement one or two fluorine atoms while maintaining high chemoselectivity remains a formidable challenge. Here we describe general strategy for sequential carbon-fluorine (C-F) bond functionalizations trifluoroacetamides and trifluoroacetates. The reaction begins with activation carbonyl oxygen atom by 4-dimethylaminopyridine-boryl radical, followed spin-center shift trigger C-F scission. A chemoselectivity-controllable two-stage process enables generation difluoro- monofluoroalkyl radicals, which are selectively functionalized different radical traps afford diverse products. mechanism origin were established experimental computational approaches.

Язык: Английский

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Recent progress on selective deconstructive modes of halodifluoromethyl and trifluoromethyl-containing reagents

Chemical Society Reviews, Год журнала: 2020, Номер 49(24), С. 9197 - 9219

Опубликована: Янв. 1, 2020

Halodifluoromethyl and trifluoromethyl-containing compounds can act various rolesviaselective cleavage modes to access more valuable fluorinated or nonfluorinated molecules.

Язык: Английский

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Nickel‐CatalyzedDicarbofunctionalization of Alkenes^†

Chinese Journal of Chemistry, Год журнала: 2020, Номер 38(11), С. 1371 - 1394

Опубликована: Июнь 16, 2020

As a straightforward strategy for rapidly increasing molecular complexity, dicarbofunctionalization of alkenes has attracted substantial interests organic synthesis, medicine chemistry, and materials science. Nickel‐catalyzed cascade dicarbofunctionalizations have been flourished in this area recently, nickel‐mediated radical pathways particularly offer new opportunities conjunctive cross‐couplings with alkyl coupling partners. Herein, we give comprehensive review nickel‐catalyzed through historical perspective, including intermolecular three‐component reactions intramolecular reactions. Among the discussed review, carbometallation/cross‐coupling process addition/cross‐coupling are two major alkenes. The oxidative cyclization 1,2‐metallate shift processes also selectively discussed. These methods overcome limitations associated using noble metals field, providing an efficient access to structurally diversified molecules.

Язык: Английский

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On the Nature of C(sp³)–C(sp²) Bond Formation in Nickel-Catalyzed Tertiary Radical Cross-Couplings: A Case Study of Ni/Photoredox Catalytic Cross-Coupling of Alkyl Radicals and Aryl Halides

Journal of the American Chemical Society, Год журнала: 2020, Номер 142(15), С. 7225 - 7234

Опубликована: Март 20, 2020

The merger of photoredox and nickel catalysis has enabled the construction quaternary centers. However, mechanism, role ligand, effect spin state for this transformation related Ni-catalyzed cross-couplings involving tertiary alkyl radicals in combination with bipyridine diketonate ligands remain unknown. Several mechanisms have been proposed, all invoking a key Ni(III) species prior to undergoing irreversible inner-sphere reductive elimination. In work, we used open-shell dispersion-corrected DFT calculations, quasi-classical dynamics experiments study detail mechanism carbon–carbon bond formation Ni bipyridine- diketonate-based catalytic systems. These calculations revealed that access high states (e.g., triplet tetrahedral Ni(II) species) is critical effective radical cross-coupling radicals. Further, these disparate C–C formation. Specifically, contrary neutral Ni-bipyridyl system, lead directly corresponding products via an outer-sphere elimination step from intermediates. Implications design new transformations are discussed.

Язык: Английский

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Recent advance in the C–F bond functionalization of trifluoromethyl-containing compounds

Organic Chemistry Frontiers, Год журнала: 2021, Номер 8(14), С. 3915 - 3942

Опубликована: Янв. 1, 2021

The C–F bond is the strongest single in organic compounds.

Язык: Английский

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Photochemical C–F Activation Enables Defluorinative Alkylation of Trifluoroacetates and -Acetamides

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(47), С. 19648 - 19654

Опубликована: Ноя. 18, 2021

The installation of gem-difluoromethylene groups into organic structures remains a daunting synthetic challenge despite their attractive structural, physical, and biochemical properties. A very efficient retrosynthetic approach would be the functionalization single C–F bond from trifluoromethyl group. Recent advances in this line attack have enabled activation trifluoromethylarenes, but limit accessible motifs to only benzylic gem-difluorinated scaffolds. In contrast, trifluoroacetates enable use as bifunctional synthon. Herein, we report photochemically mediated method for defluorinative alkylation commodity feedstock: ethyl trifluoroacetate. novel mechanistic was identified using our previously developed diaryl ketone HAT catalyst hydroalkylation diverse suite alkenes. Furthermore, electrochemical studies revealed that more challenging radical precursors, namely trifluoroacetamides, could also functionalized via synergistic Lewis acid/photochemical activation. Finally, concise gem-difluoro analogs FDA-approved pharmaceutical compounds.

Язык: Английский

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Visible-Light-Induced Palladium-Catalyzed Selective Defluoroarylation of Trifluoromethylarenes with Arylboronic Acids

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(34), С. 13971 - 13979

Опубликована: Авг. 19, 2021

Selective functionalization of inactive C(sp3)-F bonds to prepare medicinally interesting aryldifluoromethylated compounds remains challenging. One promising route is the transition-metal-catalyzed cross-coupling through oxidative addition bond in trifluoromethylarenes (ArCF3), which are ideal precursors for this process due their ready availability and low cost. Here, we report an unprecedented excited-state palladium catalysis strategy selective defluoroarylation with arylboronic acids. This visible-light-induced palladium-catalyzed proceeds under mild reaction conditions allows transformation a variety acids ArCF3. Preliminary mechanistic studies reveal that ArCF3 palladium(0) via single electron transfer pathway responsible activation.

Язык: Английский

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Recent Advances in the Synthesis of Difluorinated Architectures from Trifluoromethyl Groups

Advanced Synthesis & Catalysis, Год журнала: 2021, Номер 364(2), С. 234 - 267

Опубликована: Ноя. 29, 2021

Abstract Fluorine‐containing moieties are widely used in the pharmaceutical, agrochemical, and material fields. Thus, these structures of immense interest fields organic synthesis medicinal chemistry. Among various fluorinated groups, difluoromethyl unit has drawn increasing attention due to its unique pharmaceutical properties. In recent years, several methods for difluoromethylated compounds have been rapidly developed. However, most treat aromatic with excess difluoromethylating reagents, which often contain organometallic compounds, so transformations generally less environmentally friendly atom‐economical. this review, we summarize development new motifs or difluoroalkenes from trifluoromethylated trifluoromethyl alkenes via single C( sp 3 )−F bond cleavage. magnified image

Язык: Английский

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Photochemical and electrochemical strategies in C–F bond activation and functionalization

Organic Chemistry Frontiers, Год журнала: 2021, Номер 9(3), С. 853 - 873

Опубликована: Дек. 7, 2021

The recent advances in photochemical or electrochemical C–F bond activation and functionalization have been summarized discussed.

Язык: Английский

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