Recent topics of radical-based carbon-carbon bond formations

Deepthi, Ani; Sathi, Vidya; Nair, Vijay

doi:10.1016/j.tetlet.2018.06.029

Cited by 10 publications

(4 citation statements)

References 95 publications

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“…In the past decade, radical reactions have attracted increasing attention in the field of synthetic organic chemistry due to their high functional group tolerance, mild reaction condition, and the presence of noncharged intermediates . In general, free radicals are highly reactive, which makes radical reactions lack the desired selectivity.…”

Section: Introductionmentioning

confidence: 99%

Insights into the Mechanism of Metal-Catalyzed Transformation of Oxime Esters: Metal-Bound Radical Pathway vs Free Radical Pathway

et al. 2022

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Controlling of radical reactivity by binding a radical to the metal center is an elegant strategy to overcome the challenge that radical intermediates are "too reactive to be selective". Yet, its application has seemingly been limited to a few strained-ring substrates, azide compounds, and diazo compounds. Meanwhile, first-row transition-metal-catalyzed (mainly, Fe, Ni, Cu) transformations of oxime esters have been reported recently in which the activation processes are assumed to follow free-radical mechanisms. In this work, we show by means of density functional theory calculations that the activation of oxime esters catalyzed by Fe(II) and Cu(I) catalysts more likely affords a metal-bound iminyl radical, rather than the presumed free iminyl radical, and the whole process follows a metal-bound radical mechanism. The as-formed metal-bound radical intermediates are an Fe(III)-iminyl radical (S total = 2, S Fe = 5/2, and S iminyl = −1/2) and a Cu(II)-iminyl radical (S total = 0, S Cu = 1/2, and S iminyl = −1/2). The discovery of such novel substrates affording metal-bound radical intermediates may facilitate the experimental design of metal-catalyzed asymmetric synthesis using oxime esters to achieve the desired enantioselectivity.

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Section: Introductionmentioning

confidence: 99%

Insights into the Mechanism of Metal-Catalyzed Transformation of Oxime Esters: Metal-Bound Radical Pathway vs Free Radical Pathway

et al. 2022

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“…The photosensitized formation of a radical anion, followed by reduction of an aryl halide, has been shown to initiate C−C bond formation. 2 Energetic radicals may also initiate H atom abstractions. Hydroxyl radical, for example, is a highly reactive species that is useful to oxidatively cross-link the binding sites of weakly bound macromolecule assemblies.…”

Section: ■ Introductionmentioning

confidence: 99%

“…One of the most fundamental reactions in organic chemistry is radical–radical recombination to form a carbon–carbon bond. The thermal production of radicals widely employ halogens or transition metal catalysts that are not environmentally compatible. , Photochemistry offers the opportunity to create in excess of 3 eV of energy per absorbed UV photon. Photoinduced electron transfer (PET) is a useful way to make bond-forming radicals via either inter- or intramolecular sensitization processes.…”

Section: Introductionmentioning

confidence: 99%

“…Photoinduced electron transfer (PET) is a useful way to make bond-forming radicals via either inter- or intramolecular sensitization processes. The photosensitized formation of a radical anion, followed by reduction of an aryl halide, has been shown to initiate C–C bond formation . Energetic radicals may also initiate H atom abstractions.…”

Section: Introductionmentioning

confidence: 99%

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Formation and Reaction Kinetics of Biradicals and Triplet States in a Series of Carboxylated 1,4,5,8-Naphthalene Diimides

Sova

Kelly

2020

J. Phys. Chem. A

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The singlet-state deactivation products in a series of alkyl carboxylate substituted 1,4,5,8-naphthalene diimide (NDI) compounds were characterized using fluorescence and phosphorescence spectroscopies, as well as nanosecond laser flash photolysis. The reactive intermediates were quantified as a function of the number of methylenes in the alkyl linker. Rate constants for photoinduced electron transfer (PET) to the singlet excited state of the NDIs varied from 1.2 × 1010 to 4.9 × 1010 s–1. The yield of the long-lived amino ketyl radical ranged from 15% to 60% in compounds having 4 to 1 intervening methylenes between the NDI chromophore and the covalently attached carboxylic acid. A predominantly triplet state was observed upon direct excitation of the compound having the slowest PET. This T1 state of the NDIs was reductively quenched by DABCO electron donor. The amino ketyl radical was unreactive toward electron donors but was found to react with the hydrogen atom donor β-mercaptoethanol. The compounds comprise a novel class of long-wavelength and strongly absorbing UV-activated chromophores that generate carbon-centered biradicals via direct 355 nm excitation in the absence of a cosensitizer.

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Tandemreaktionen aus anionischer Oxy‐Cope‐Umlagerung und Oxygenierung als vielseitiger Zugang zu verschiedenartigen Gerüsten

et al. 2020

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Tandemreaktionen aus anionischer Oxy‐Cope‐Umlagerung und Radikaloxygenierung ergeben δ,ϵ‐ungesättigte α‐(Aminoxy)carbonylverbindungen, die sich als vielseitige Vorläufer für verschiedenartige Verbindungsklassen eignen. Funktionalisierte Carbocyclen werden durch sehr seltene 5‐endo‐trig, aber auch gebräuchlichere 5‐exo‐trig Radikalcyclisierungen durch Nutzung des persistenten Radikaleffekts erhalten. Die Tandemreaktionen können durch hochdiastereoselektive Allylierungs‐ oder Reduktionsschritte erweitert werden, die zu komplexen Gerüsten führen.

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Recent topics of radical-based carbon-carbon bond formations

Cited by 10 publications

References 95 publications

Insights into the Mechanism of Metal-Catalyzed Transformation of Oxime Esters: Metal-Bound Radical Pathway vs Free Radical Pathway

Insights into the Mechanism of Metal-Catalyzed Transformation of Oxime Esters: Metal-Bound Radical Pathway vs Free Radical Pathway

Formation and Reaction Kinetics of Biradicals and Triplet States in a Series of Carboxylated 1,4,5,8-Naphthalene Diimides

Tandemreaktionen aus anionischer Oxy‐Cope‐Umlagerung und Oxygenierung als vielseitiger Zugang zu verschiedenartigen Gerüsten

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