- A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics
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The kinetics of quinuclidine displacement of BH3 from a wide range of Lewis base borane adducts have been measured. Parameterization of these rates has enabled the development of a nucleofugality scale (NFB), shown to quantify and predict the leaving group ability of a range of other Lewis bases. Additivity observed across a number of series R′3-nRnX (X = P, N; R′ = aryl, alkyl) has allowed the formulation of related substituent parameters (nfPB, nfAB), providing a means of calculating NFB values for a range of Lewis bases that extends far beyond those experimentally derived. The utility of the nucleofugality parameter is explored by the correlation of the substituent parameter nfPB with the hydrolyses rates of a series of alkyl and aryl MIDA boronates under neutral conditions. This has allowed the identification of MIDA boronates with heteroatoms proximal to the reacting center, showing unusual kinetic lability or stability to hydrolysis.
- García-Domínguez, Andrés,Gonzalez, Jorge A.,Leach, Andrew G.,Lloyd-Jones, Guy C.,Nichol, Gary S.,Taylor, Nicholas P.
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supporting information
(2022/01/04)
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- Ready approach to poly(vinyldiphenylphosphine): A novel soluble polymer for conveniently conducting Wittig reactions
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The novel poly(vinyldiphenylphosphine) could be easily prepared by using the reactions of the cheap poly(vinyl chloride) with sodium phosphides. Poly(vinyldiphenylphosphine) is soluble in common solvents while its corresponding phosphine oxide is hardly soluble in the solvents. Taking advantage of this different solubility, poly(vinyldiphenylphosphine) could be used as a soluble phosphinopolymer for the Wittig reactions. The reactions could take place efficiently to produce the corresponding olefins while the isolation of the products were simple since the resulted poly(vinyldiphenylphosphine oxide) was not soluble in the solvent and could be easily removed by filtration.
- Ye, Jing-Jing,Han, Li-Biao
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supporting information
(2021/01/25)
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- Direct and Scalable Electroreduction of Triphenylphosphine Oxide to Triphenylphosphine
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The direct and scalable electroreduction of triphenylphosphine oxide (TPPO)-the stoichiometric byproduct of some of the most common synthetic organic reactions-to triphenylphosphine (TPP) remains an unmet challenge that would dramatically reduce the cost and waste associated with performing desirable reactions that are mediated by TPP on a large scale. This report details an electrochemical methodology for the single-step reduction of TPPO to TPP using an aluminum anode in combination with a supporting electrolyte that continuously regenerates a Lewis acid from the products of anodic oxidation. The resulting Lewis acid activates TPPO for reduction at mild potentials and promotes P-O over P-C bond cleavage to selectively form TPP over other byproducts. Finally, this robust methodology is applied to (i) the reduction of synthetically useful classes of phosphine oxides, (ii) the one-pot recycling of TPPO generated from a Wittig reaction, and (iii) the gram-scale reduction of TPPO at high concentration (1 M) with continuous product extraction and in flow at high current density.
- Manabe, Shuhei,Sevov, Christo S.,Wong, Curt M.
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p. 3024 - 3031
(2020/03/10)
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- Versatile Visible-Light-Driven Synthesis of Asymmetrical Phosphines and Phosphonium Salts
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Asymmetrically substituted tertiary phosphines and quaternary phosphonium salts are used extensively in applications throughout industry and academia. Despite their significance, classical methods to synthesize such compounds often demand either harsh reaction conditions, prefunctionalization of starting materials, highly sensitive organometallic reagents, or expensive transition-metal catalysts. Mild, practical methods thus remain elusive, despite being of great current interest. Herein, we describe a visible-light-driven method to form these products from secondary and primary phosphines. Using an inexpensive organic photocatalyst and blue-light irradiation, arylphosphines can be both alkylated and arylated using commercially available organohalides. In addition, the same organocatalyst can be used to transform white phosphorus (P4) directly into symmetrical aryl phosphines and phosphonium salts in a single reaction step, which has previously only been possible using precious metal catalysis.
- Arockiam, Percia Beatrice,Lennert, Ulrich,Graf, Christina,Rothfelder, Robin,Scott, Daniel J.,Fischer, Tillmann G.,Zeitler, Kirsten,Wolf, Robert
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supporting information
p. 16374 - 16382
(2020/11/03)
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- Decarboxylative Phosphine Synthesis: Insights into the Catalytic, Autocatalytic, and Inhibitory Roles of Additives and Intermediates
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Phosphines are among the most widely used ligands, catalysts, and reagents. Current synthetic approaches to phosphines are dominated by nucleophilic displacement reactions with organometallic reagents. Here, we report a radical-based approach to phosphines that proceeds by a cross-electrophile coupling of chlorophosphines and redox-active esters. The reaction allows for the synthesis of a broad range of substituted phosphines that were not readily attainable with the present methods. Our experimental and DFT computational studies also clarified the catalytic, autocatalytic, and inhibitory roles of additives and intermediates, as well as the mechanistic details of the photocatalytic and zinc-mediated redox modes that can have implications for the mechanistic interpretation of other cross-electrophile coupling reactions.
- Jin, Shengfei,Haug, Graham C.,Nguyen, Vu T.,Flores-Hansen, Carsten,Arman, Hadi D.,Larionov, Oleg V.
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p. 9764 - 9774
(2019/10/14)
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- Reduction of phosphine oxides to the corresponding phosphine derivatives in Mg/Me3SiCl/DMI system
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Direct reductions of phosphine oxides to the corresponding phosphines were performed successfully by using Mg/Me3SiCl/DMI system. The reduction proceeded under mild conditions and was applicable to a wide range of phosphine oxides; triarylphosphine oxides, alkyldiarylphosphine oxides, and dialkylarylphosphine oxides gave the corresponding phosphines in good to excellent yields.
- Kuroboshi, Manabu,Kita, Toshihito,Aono, Asuka,Katagiri, Toshimasa,Kikuchi, Seiya,Yamane, Syoko,Kawakubo, Hiromu,Tanaka, Hideo
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p. 918 - 920
(2015/02/05)
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- Efficient catalytic hydrogenation of levulinic acid: A key step in biomass conversion
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γ-Valerolactone (GVL) has been proposed as a sustainable liquid, and could be used for the production of hydrocarbons by using both homogeneous and heterogeneous catalytic systems. The selective reduction of levulinic acid (LA) to GVL is a key transformation for biorefinery concepts based on platform molecules. We report a detailed investigation of the conversion of LA to GVL using molecular hydrogen in the presence of a catalyst in situ generated from Ru(acac)3, and electronically and sterically characterized alkyl-bis(m-sulfonated-phenyl)- and dialkyl-(m-sulfonated-phenyl)phosphine (RnP(C6H4-m-SO3Na)3-n (n = 1 or 2; R = Me, Pr, iPr, Bu, Cp) ligands. The hydrogenation experiments were performed in the range of 5-100 bar H2 at 140 °C using 0.016 mol% catalyst and 5-20 eqv. of ligand. The effects of hydrogen pressure and Ru/ligand ratio on the LA conversion were determined. The nBuP(C 6H4-m-SO3Na)2 (χ = 12.5, Tol = 153°) showed the highest activity achieving turnover numbers up to 6200 with a yield and selectivity higher than 99% in a solvent, chlorine and promoter free reaction mixture. The catalyst was successfully recycled for six consecutive runs without loss of activity. The characterization of sulfonated and non-sulfonated phosphines indicated that the sulfonation had no significant effect on the steric and electronic properties of the ligands. The Royal Society of Chemistry 2012.
- Tukacs, Jozsef M.,Kiraly, David,Stradi, Andrea,Novodarszki, Gyula,Eke, Zsuzsanna,Dibo, Gabor,Kegl, Tamas,Mika, Laszlo T.
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supporting information; experimental part
p. 2057 - 2065
(2012/08/14)
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- Electroreduction of triphenylphosphine oxide to triphenylphosphine in the presence of chlorotrimethylsilane
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Electroreduction of triphenylphosphine oxide to triphenylphosphine in an acetonitrile solution of tetrabutylammonium bromide in the presence of chlorotrimethylsilane was performed successfully in an undivided cell fitted with a zinc anode and a platinum cathode under constant current. A plausible mechanism involving, (1) one-electron reduction of triphenylphosphine oxide generating the corresponding anion radical [Ph3P-O-], (2) subsequent reaction with chlorotrimethylsilane affording the (trimethylsiloxy)triphenylphosphorus radical [Ph3P-OSiMe 3], and (3) further one-electron reduction followed by P-O bond fission leading to triphenylphosphine is proposed. In a similar manner, electroreduction of some triarylphosphine oxides and alkyldiarylphosphine oxides was executed to give the corresponding phosphine derivatives in good to moderate yields. Georg Thieme Verlag Stuttgart · New York.
- Kawakubo, Hiromu,Kuroboshi, Manabu,Yano, Tomotake,Kobayashi, Kazuma,Kamenoue, Syogo,Akagi, Tomomi,Tanaka, Hideo
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scheme or table
p. 4091 - 4098
(2012/01/12)
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- Synthesis of alkyl- and aryldiphenylphosphines via electrogenerated magnesium chloride diphenylphosphanide
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A two-steps procedure allowing the formation of alkyldiphenylphosphines and aryldiphenylphosphines in good yield is described. It relies on the electrochemical preparation of magnesium chloride diphenylphosphanide and its subsequent coupling with either alkyl halides or aryl fluorides.
- Nechab, Malek,Le Gall, Erwan,Troupel, Michel,Nédélec, Jean-Yves
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p. 1809 - 1813
(2007/10/03)
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- CsOH-promoted P-alkylation: A convenient and highly efficient synthesis of tertiary phosphines
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A mild and efficient method for the synthesis of tertiary phosphines and ditertiary phosphines has been developed. In the presence of cesium hydroxide, molecular sieves and DMF at room temperature, various secondary phosphines and alkyl bromides were examined, and the results have demonstrated that this methodology offers a general synthetic procedure to produce tertiary phosphines in moderate to high yields. Optically active tertiary phosphine synthesis is also described.
- Honaker, Matthew T.,Sandefur, Benjamin J.,Hargett, James L.,McDaniel, Alicia L.,Salvatore, Ralph Nicholas
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p. 8373 - 7377
(2007/10/03)
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- Alane - A novel way to reduce phosphine oxides
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Phosphine oxides may be reduced to phosphines in excellent yield using alane - AIH3. An aqueous workup is not required.
- Griffin, Sara,Heath, Lucy,Wyatt, Paul
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p. 4405 - 4406
(2007/10/03)
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- Process for the preparation of bulky alkyldiarylphosphines and unsymmetrical aryldialkyl phosphines
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A process for the selective production of bulky alkyldiarylphosphines and unsymmetrical dialkylarylphosphines comprising reacting a first Grignard reagent having a bulky alkyl group with an aryldichlorophosphine and thereafter and without isolating the resulting bulky alkylarylchlorophosphine intermediate, reacting said intermediate with a second Grignard reagent having a different, less bullky alkyl group or an aryl group to provide the product phosphine.
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