- Potent Reductants via Electron-Primed Photoredox Catalysis: Unlocking Aryl Chlorides for Radical Coupling
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We describe a new catalytic strategy to transcend the energetic limitations of visible light by electrochemically priming a photocatalyst prior to excitation. This new catalytic system is able to productively engage aryl chlorides with reduction potentials hundreds of millivolts beyond the potential of Na0 in productive radical coupling reactions. The aryl radicals produced via this strategy can be leveraged for both carbon-carbon and carbon-heteroatom bond-forming reactions. Through direct comparison, we illustrate the reactivity and selectivity advantages of this approach relative to electrolysis and photoredox catalysis.
- Chernowsky, Colleen P.,Cowper, Nicholas G. W.,Wickens, Zachary K.,Williams, Oliver P.
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supporting information
(2020/02/04)
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- Avisible-light-promoted metal-free strategy towards arylphosphonates: Organic-dye-catalyzed phosphorylation of arylhydrazines with trialkylphosphites
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A visible-light-induced metal-free catalytic system was developed for the synthesis of arylphosphonates starting from arylhydrazines and trialkylphosphites. By using the inexpensive eosin B as catalyst, sub-stoichiometric amounts of DABCO, and ambient air as oxidant, diverse arylphosphonates were obtained under visible-light irradiation. Notably, this catalytic system is suitable for gram-scale reaction by utilizing sunlight as an illumination source.
- Li, Rui,Chen, Xiaolan,Wei, Shengkai,Sun, Kai,Fan, Lulu,Liu, Yan,Qu, Lingbo,Zhao, Yufen,Yu, Bing
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supporting information
p. 4807 - 4813
(2018/12/11)
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- Aryl phosphate esters compound and preparation method thereof
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The invention discloses an aryl phosphate esters compound and a preparation method thereof, wherein an organic dye is used as a photosensitizer, a catalytic amount of alkali is added, aryl hydrazine and phosphate are used as reactants, acetonitrile is used as a solvent, the temperature is controlled between 25-45 DEG C, the reaction is carried out under the irradiation of visible light for 1-6h, and the product aryl phosphate compound is separated by column chromatography. The invention provides a new method for synthesizing aryl phosphate class target compound with cheap and easily availablearyl hydrazine and phosphate ester compound as starting material for the first time. The preparation method has the advantages of mild reaction conditions, simple operation and the like; in the drug synthesis, the residual of the metal catalyst brings great trouble to the production and application of the drug, so that the metal-free catalytic system in the method has great potential application value.
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Paragraph 0022-0025; 0051-0053
(2018/10/11)
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- Visible-Light-Mediated Metal-Free Synthesis of Aryl Phosphonates: Synthetic and Mechanistic Investigations
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This work describes a straightforward access to a large variety of aryl phosphonates by the simple combination of diaryliodonium salts with phosphites in the presence of a base and under visible-light illumination. The reaction proceeds smoothly, tolerates various functionalities, and was applied for the synthesis of pharmaceutically relevant compounds. Mechanistic investigations, including EPR, NMR, and DFT calculations, support the postulated reaction mechanism.
- Lecroq, William,Bazille, Pierre,Morlet-Savary, Fabrice,Breugst, Martin,Lalevée, Jacques,Gaumont, Annie-Claude,Lakhdar, Sami
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supporting information
p. 4164 - 4167
(2018/07/29)
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- Ar-P bond construction by the Pd-catalyzed oxidative cross-coupling of arylsilanes with H-phosphonates via C-Si bond cleavage
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A novel and efficient methodology that allows for the construction of Ar-P bonds via the Pd-catalyzed oxidative cross-coupling reaction of various arylsilanes with H-phosphonates leading to valuable arylphosphonates has been developed.
- Luo, Haiqing,Liu, Haidong,Chen, Xingwei,Wang, Keke,Luo, Xuzhong,Wang, Kejun
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supporting information
p. 956 - 958
(2017/01/17)
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- A palladium-catalyzed oxidative cross-coupling reaction between aryl pinacol boronates and H-phosphonates in ethanol
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The first successful oxidative coupling reaction of aryl pinacol boronic esters with H-phosphonates to deliver aryl phosphorous compounds is reported herein. These reactions between aryl boronic reagents and H-phosphonates were carried out synergistically using a Pd catalyst, additive and oxidant. Without using bases and ligands, phosphorylation was accomplished in an environmentally-friendly manner under mild conditions in ethanol.
- Chen, Te-Hsuan,Reddy, Daggula Mallikarjuna,Lee, Chin-Fa
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p. 30214 - 30220
(2017/07/07)
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- Acetic acid mediated synthesis of phosphonate-substituted titanium oxo clusters
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New phosphonate/acetate-substituted titanium oxo/alkoxo clusters were prepared from Ti(OiPr)4 and bis(trimethylsilyl) phosphonates in the presence of acetic acid, which served to generate water in situ through ester formation. The process led to clusters with a higher degree of condensation than in previously known phosphonate-substituted titanium oxo clusters. The clusters [Ti6O4(OiPr)10(OAc)2(O3PR)2] (OAc = acetate) were obtained for a large variety of functional and non-functional groups R under a range of reaction conditions. This cluster type, which is also retained in solution, therefore appears to be very robust. Two other clusters, [Ti5O(OiPr)11(OAc)(O3PCH2CH2CH2Br)3] and [Ti5O3(OiPr)6(OAc)4(O3P-xylyl)2], were only isolated in special cases. Several acetate/phosphonate-substituted titanium cage compounds were obtained from the reaction of titanium isopropoxide with bis(trimethylsilyl) phosphonates in the presence of acetic acid as water generator.
- Czakler, Matthias,Artner, Christine,Schubert, Ulrich
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p. 2038 - 2045
(2015/04/27)
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- CuSO4/Al2O3 as a new effective and recyclable catalyst for the arylation of dialkyl phosphites
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A new effective recycled catalyst CuSO4/Al2O 3, which performs the phosphorylation of aryl halides and bromostyrene, was proposed.
- Karlstedt,Anokhin,Beletskaya
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p. 2498 - 2499
(2014/11/08)
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- Nickel-catalyzed Arbuzov reactions of aryl triflates with triethyl phosphite
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An efficient method was developed for the nickel-catalyzed phosphonylation of aryl triflates with triethyl phosphite, in which KBr as an additive promoted the SN2 catalytic step. To the best of our knowledge, this is the first example of nickel
- Yang, Guoqiang,Shen, Chaoren,Zhang, Liang,Zhang, Wanbin
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supporting information; experimental part
p. 5032 - 5035
(2011/10/09)
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- Arenediazonium tetrafluoroborates in palladium-catalyzed C-P bond-forming reactions. Synthesis of arylphosphonates, -phosphine oxides, and -phosphines
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A novel palladium-catalyzed synthesis of arylphosphonates from arenediazonium tetrafluoroborates and triethylphosphite or diethylphosphite is presented. The reaction tolerates useful substituents including bromo, chloro, nitro, ether, cyano, keto, and ester groups, can be performed as a one-pot process from anilines omitting the isolation of arenediazonium salts, and can be extended to the preparation of arylphosphine oxides and arylphosphines.
- Berrino, Roberta,Cacchi, Sandro,Fabrizi, Giancarlo,Goggiamani, Antonella,Stabile, Paolo
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supporting information; experimental part
p. 4518 - 4520
(2010/11/17)
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- Oxidative Phoshonylation of Aromatics with Ammonium Cerium(IV) Nitrate
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Arylphosphonates 5 and 6 can be prepared in good yields in a one-step synthesis starting from arenes with tri- or diethylphosphites and cerium ammonium nitrate (CAN) as oxidant.The seletivity of the oxidative phosphonylation is relatively low; the reactive species is a phosphite radical cation.
- Kottmann, Hariolf,Skarzewski, Jacek,Effenberger, Franz
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p. 797 - 801
(2007/10/02)
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- OXIDATIVE PHOSPHONYLATION OF AROMATIC COMPOUNDS
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Aryl phosphonates can be prepared in good yield from the respective arenes and tri- or dialkylphosphites by either chemical or anodic oxidation.The anodic oxidation proceeds either via phosphinium radical cations, which then attack the arenes electrophilically, or via arene radical cations, which add the trialkylphosphite as nucleophile.Aryl phosphonates are also obtained in good yield by chemical oxidation with peroxodisulfate/AgNO3 in acetonitrile/water or glacial acetic acid.The diethylphosphinium radical cation, formed from diethylphosphite by oxidation with Ag(II), is supposed to be the reactive species in this process.Raising the silver salt concentration leads to an increase in polyphosphonylation.Selectivity ratios were determined for the oxidative phosphonylation process.
- Effenberger, Franz,Kottmann, Hariolf
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p. 4171 - 4182
(2007/10/02)
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- Some Rearrangements of Unsaturated Phosphonate Esters
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α-Hydroxyalk-2-enylphosphonates undergo Claisen orthoester rearrangement on heating with orthoesters, and their arylsulphenates undergo -sigmatropic rearrangement to give 3-arylsulphinylalk-1-enylphosphonates.The addition of allyloxide anion to the central carbon of the allene Me2C=C=CHP(O)(OEt)2 is followed by rapid Claisen rearrangement of the resulting allylic carbanion to give the two possible β-ketoalkylphosphonates.Allenic phosphonates of the general formula R1R2C=CHnCR3=C=CHP(O)(OEt)2 have been prepared: when R1 = R2 = H, R3 = Me, and n = 2, Cope rearrangement occurs to give isomeric dienes; when R1,R2,R3 = Me and n = 0, hydride shift gives a triene which then cyclises to a cyclohexadiene; when R1 = Me, R2 = H, R3 = H or Me, and n = 0, the diene component can be used in Diels-Alder reactions.
- Cooper, Dianne,Trippett, Stuart
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p. 2127 - 2133
(2007/10/02)
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