Site-selective and metal-free C–H phosphonation of arenes <i>via</i> photoactivation of thianthrenium salts

Gallego-Gamo, Albert; Reyes-Mesa, David; Guinart-Guillem, Axel; Pleixats, Roser; Gimbert-Suriñach, Carolina; Vallribera, Adelina; Granados, Albert

doi:10.1039/d3ra04512a

Cited by 14 publications

(5 citation statements)

References 46 publications

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“…[6a] These aryl radical precursors were successfully subjected to our standard reaction conditions. Trifluoromethyl (15) and methyl ester (16) derivatives in meta position were isolated in 65 and 58% yield, respectively. Of note, this transformation tolerates a C(sp 2 )À NO 2 bond, obtaining compound 17 in moderate 34% yield.…”

Section: Resultsmentioning

confidence: 99%

“…Typically, when the acceptor molecule bears a leaving group, the generated intermediate can undergo an irreversible homolytic fragmentation to form high-energy radical species that can be engaged in various transformations. [12] Among the library of feasible electron-donors amenable to TTs EDA complex chemistry, the use of amines, [13] thiolates, [14] sulfinates, [15] phosphites [16] or electronically rich borylated cathecols [17] has been reported (Scheme 1A). Particularly interesting are the methods presented by Procter and co-workers where they demonstrate that triarylamine-derivatives [13a] or carbonate salts [1h] are suitable electron-donors in sulfonium salts EDA complex chemistry.…”

Section: Introductionmentioning

confidence: 99%

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Access to Benzyl Oxindoles via Electron Donor‐Acceptor Complex Photoactivation Using Thianthrenium Salts and Potassium Carbonate

Sarró,

Gallego‐Gamo,

Pleixats

et al. 2024

Adv Synth Catal

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A photochemical synthesis of biologically relevant benzyl oxindoles is presented via electron‐donor acceptor (EDA) complex strategy. This exogenous photocatalyst‐free method describes the formation of a new electron donor‐acceptor complex based on potassium carbonate and thianthrenium salts for C(sp2)–C(sp3) bond formation. This transition‐metal free reaction allows a rapid increase in oxindoles molecular complexity chemical space, tolerating different functional groups as well as sophisticated biomolecules. The scalability and sustainability of this method is highlighted by an important waste recovery protocol. Mechanistic investigations support the formation of an EDA complex that induces a radical chain, and the applicability of this method is showcased by straightforward derivatization reactions.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Access to Benzyl Oxindoles via Electron Donor‐Acceptor Complex Photoactivation Using Thianthrenium Salts and Potassium Carbonate

Sarró,

Gallego‐Gamo,

Pleixats

et al. 2024

Adv Synth Catal

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View full text Add to dashboard Cite

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“…[62] Introduction of dithiocarbamate fragments into aromatic systems through EDAbased conversion of 59, accomplished in aqueous medium through micellar catalysis, has been demonstrated by Yang and colleagues. [63] Conversion of arenes to sulfonium salts allows for smooth introduction of boronate and phosphonate moieties, as disclosed by the Rueping [64] and Granados groups [65] (Scheme 37). Conversion of the starting materials in accordance with these methods is generally high, with 36 being isolated in 36-92 % yields [64] and 35 in 35-95 % yields.…”

Section: S-aryl Thiantrenium and Dibenzothiophenium Saltsmentioning

confidence: 99%

“…Conversion of the starting materials in accordance with these methods is generally high, with 36 being isolated in 36-92 % yields [64] and 35 in 35-95 % yields. [65] Advantages of these protocols include their compatibility with para-and metasubstituted substrates, inertness towards highly reactive hydroxyl and carbonyl groups, as well as halogens, and applicability to late-stage CÀ H functionalization of bioactive molecules, such as estrone and clofibrate.…”

Section: S-aryl Thiantrenium and Dibenzothiophenium Saltsmentioning

confidence: 99%

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

Volkov,

Bugaenko,

Karchava

2024

ChemCatChem

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

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“…The authors have cited additional references within the Supporting Information. [44][45][46][47][48][49][50][51][52][53][54][55][56][57]…”

Section: Zuschriftmentioning

confidence: 99%

Electrochemical Generation of Aryl Radicals from Organoboron Reagents Enabled by Pulsed Electrosynthesis

Boudjelel,

Zhong,

Ballerini

et al. 2024

Angewandte Chemie

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Aryl radicals play a pivotal role as reactive intermediates in chemical synthesis, commonly arising from aryl halides and aryl diazo compounds. Expanding the repertoire of sources for aryl radical generation to include abundant and stable organoboron reagents would significantly advance radical chemistry and broaden their reactivity profile. While traditional approaches utilize stoichiometric oxidants or photocatalysis to generate aryl radicals from these reagents, electrochemical conditions have been largely underexplored. Through rigorous mechanistic investigations, we identified fundamental challenges hindering aryl radical generation. In addition to the high oxidation potentials of aromatic organoboron compounds, electrode passivation through radical grafting, homocoupling of aryl radicals, and decomposition issues were identified. We demonstrate that pulsed electrosynthesis enables selective and efficient aryl radical generation by mitigating the fundamental challenges. Our discoveries facilitated the development of the first electrochemical conversion of aryl potassium trifluoroborate salts into aryl C–P bonds. This sustainable and straightforward oxidative electrochemical approach exhibited a broad substrate scope, accommodating various heterocycles and aryl chlorides, typical substrates in transition‐metal catalyzed cross‐coupling reactions. Furthermore, we extended this methodology to form aryl C–Se, C–Te, and C–S bonds, showcasing its versatility and potential in bond formation processes.

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Site-selective and metal-free C–H phosphonation of arenes via photoactivation of thianthrenium salts

Abstract: Aryl phosphonates are accessed by visible-light irradiation of new EDA complex between thianthrenium salts as electron-acceptors and phosphites as electron-donor molecules.

Cited by 14 publications

References 46 publications

Access to Benzyl Oxindoles via Electron Donor‐Acceptor Complex Photoactivation Using Thianthrenium Salts and Potassium Carbonate

Access to Benzyl Oxindoles via Electron Donor‐Acceptor Complex Photoactivation Using Thianthrenium Salts and Potassium Carbonate

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

Electrochemical Generation of Aryl Radicals from Organoboron Reagents Enabled by Pulsed Electrosynthesis

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