Synthesis of quaternary aryl phosphonium salts: photoredox-mediated phosphine arylation

Fearnley, A. F.; An, Jie; Jackson, Matthew S.; Lindovska, Petra; Denton, Ross M.

doi:10.1039/c6cc00556j

Cited by 42 publications

(17 citation statements)

References 55 publications

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“…König utilizes this highly reducing state to promote SET with an aryl bromide 31 , affording an aryl radical 32 that then reacts with P(OEt) 3 to generate phosphoranyl radical 33 . 21 Phosphoranyl radical 33 then undergoes β-scission to form product 34 and an ethyl radical, which undergoes hydrogen atom transfer (HAT) to generate ethane (note that this mechanism proceeds via the less common, radical Arbuzov-like β-scission pathway discussed earlier, see Scheme 4 ). Several other groups have also reported similar processes to König ( Scheme 7 ), whereby photocatalytically generated aryl radicals add into phosphites resulting in the formation of phosphonates.…”

Section: Radical Addition Into a Phosphine Derivativementioning

confidence: 99%

Phosphoranyl Radical Fragmentation Reactions Driven by Photoredox Catalysis

et al. 2020

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Photocatalytic generation of phosphoranyl radicals is fast emerging as an essential method for the generation of diverse and valuable radicals, typically via deoxygenation or desulfurization processes. This Perspective is a comprehensive evaluation of all studies using phosphoranyl radicals as tunable mediators in photoredox catalysis, highlighting how two distinct methods for phosphoranyl radical formation (radical addition and nucleophilic addition) can be used to generate versatile radical intermediates with diverse reactivity profiles.

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Section: Radical Addition Into a Phosphine Derivativementioning

confidence: 99%

Phosphoranyl Radical Fragmentation Reactions Driven by Photoredox Catalysis

et al. 2020

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“…These include various phosphines, alkanes, thiol, trifluoroborate salts, etc. 16,17 Results obtained for these 49 rate constants between *Ir IV Ln •¯ and Q are summarized in Figures 2, 3 and 4 below. All quenching data is included in the supporting information.…”

Section: Resultsmentioning

confidence: 99%

Method to Predict Reagents in Iridium-Based Photoredox Catalysis

Juneau¹,

Hope²,

Malenfant³

et al. 2020

Preprint

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Visible-light photoredox catalysts with oxidizing excited states have been broadly applied in organic synthesis. Following photon absorption by the photocatalyst, electron transfer from an organic reagent is the most common mechanistic outcome for this class of reaction. Reduction potentials for organic reagents are therefore useful to predict reactivity and DFT proved to be useful as a predictive tool in this regard. Due to the complex mechanisms that follow electron transfer, kinetics play a crucial role in the success of photoredox reactions. We extend the predictive tools of DFT to estimate the electron transfer rates between an excited photocatalyst and various organic substrates. To calibrate our model, 49 electron transfer rate constants were experimentally measured in acetonitrile for the catalyst Ir[dF(CF3)ppy]2(dtbpy)+. The rate constants, kq, gave a clear predictive trend when compared to calculated ionization energies in “frozen solvent”, which was a better predictor than standard reduction potentials in our case. The calculated kq gave an average error of 17% for log(kq) values between 4 and 11. This simple method can predict the reactivity of hundreds of reagents in silico. Notably, the calculations offered unexpected insight that we could translate into success for the C-H activation of acetylacetone as a proof-of-concept.

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“…This work suggested the occurrence of a charge transfer between the diaryliodonium salt and the tertiary phosphine. Enlighted by Kampmeier's work, Denton's recent work in 2016 revealed an expeditious synthesis under photoredox conditions for the preparation of quaternary aryl phoshonium salts (Figure ). The photoredox‐initiated arylation reaction between diaryliodonium triflates and triarylphosphines in the presence of a 10 W lamp and Ru(bpy) 3 Cl 2 furnished various phosphonium salts within 30 min.…”

Section: Photocatalytic Synthesis Of Phosphorus‐containing Compoundsmentioning

confidence: 99%

Photoredox Catalysis in Organophosphorus Chemistry

2017

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The vernal blooming of green chemistry has contributed to the development of visible light catalysis. Active radical species are generatedf rom catalytic amounts of photosensitizers,such as transition-metal complexes and organic dyes, upon visible light irradiation. Stoichiometrica mounts of oxidants, reductants, and radical initiators are avoidedi n most cases. Thus, reactions proceed under milder conditions with ab roader functional group tolerance than found by other methods. Photoredoxc atalysis has been used to form CÀCa nd CÀX( X= O, N, and S) bonds but is comparably underdeveloped in organophosphorus chemistry.H erein, we summarize advances in photoredox catalysis that involve organophosphorus chemistry.T he synthesis of organophosphorusc ompounds by photoredox catalysis, transition-metal complex/photoredoxd ual catalytic systems, andp hotoredox catalysis with phosphorus organocatalysts are discussed. The shortcomings and possible future trendso ft his chemistry are also presented.Scheme1.Various photocatalysts for the cross-couplingr eactionso ftetrahydroisoquinoline with dialkylphophonates and diaryl phosphine oxides[ ppy = 2phenylpyridine, bpy = 2,2'-bipyridine, DMF = N,N-dimethylformamide, AIBN = azobis(isobutyronitrile), PVA = poly(vinyl alcohol), BTF = benzotrifluoride].Scheme3.Thiophosphite-mediated RATC process to form five-membered ring and C sp 3 ÀPb ond.Scheme2.The mechanism for the photocatalyzed cross-coupling reaction [PC = Ir complex, Au complex, eosin Y, or rose bengal)].Scheme9.Direct CÀHp hosphorylationoft hiazoles in cross-coupling hydrogen evolution reaction and the proposed mechanism.Scheme11. Hetero-cross-dehydrogenative-coupling reaction of benzothiazoles and H-phosphonates.Scheme10. Hetero-cross-dehydrogenative-coupling reaction of dialkylphosphiteswith N-protected indole and the tentative reaction mechanism.

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Synthesis of quaternary aryl phosphonium salts: photoredox-mediated phosphine arylation

Cited by 42 publications

References 55 publications

Phosphoranyl Radical Fragmentation Reactions Driven by Photoredox Catalysis

Phosphoranyl Radical Fragmentation Reactions Driven by Photoredox Catalysis

Method to Predict Reagents in Iridium-Based Photoredox Catalysis

Photoredox Catalysis in Organophosphorus Chemistry

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