- 31P Nuclear Magnetic Resonance Studies of Polymer-Anchored Rhodium(I) Complexes
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Poly(4-diphenylphosphinostyrene) (1), poly(4-dicyclohexylphosphinostyrene) (2), and poly (3) were obtained by polymerization of the corresponding monomers.The polymers were treated with (RhClL2)2 and with (RhClL')2, where L and L' are ethene and 1,5-cyclooctadiene, respectively.These complexes were added stepwise and during this process the 31P NMR spectra were observed. 31P chemical shifts and 103Rh-31P coupling constants were compared with those of monomeric analogues which were treated in the same way.
- Naaktgeboren, Aart J.,Nolte, Roeland J. M.,Drenth, Wiendelt
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- Palladium-Catalyzed C-P(III) Bond Formation by Coupling ArBr/ArOTf with Acylphosphines
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Palladium-catalyzed C-P bond formation reaction of ArBr/ArOTf using acylphosphines as differential phosphination reagents is reported. The acylphosphines show practicable reactivity with ArBr and ArOTf as the phosphination reagents, though they are inert to the air and moisture. The reaction affords trivalent phosphines directly in good yields with a broad substrate scope and functional group tolerance. This reaction discloses the acylphosphines' capability as new phosphorus sources for the direct synthesis of trivalent phosphines.
- Chen, Xingyu,Wu, Hongyu,Yu, Rongrong,Zhu, Hong,Wang, Zhiqian
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p. 8987 - 8996
(2021/06/30)
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- 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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- 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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- Preparation of Aryl(dicyclohexyl)phosphines by C-P Bond-Forming Cross-Coupling in Water Catalyzed by an Amphiphilic-Resin-Supported Palladium Complex
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Aryl(dicyclohexyl)phosphines were prepared by a catalytic C-P bond-forming cross-coupling reaction of haloarenes with dicyclohexylphosphine under heterogeneous conditions in water containing an immobilized palladium complex coordinated to an amphiphilic polystyrene-poly(ethylene glycol) resin supported di(tert -butyl)phosphine ligand.
- Hirai, Yoshinori,Uozumi, Yasuhiro
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supporting information
p. 2966 - 2970
(2017/10/26)
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- NICKEL PRE-CATALYSTS AND RELATED COMPOSITIONS AND METHODS
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Described herein are nickel pre-catalysts and related compositions and methods. The nickel pre-catalysts may be activated to form catalysts which may be utilized in organic reactions.
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Page/Page column 24; 42
(2015/05/26)
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- Simplifying nickel(0) catalysis: An air-stable nickel precatalyst for the internally selective benzylation of terminal alkenes
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The synthesis and characterization of the air-stable nickel(II) complex trans-(PCy2Ph)2Ni(o-tolyl)Cl is described in conjunction with an investigation of its use for the Mizoroki-Heck-type, room temperature, internally selective coupling of substituted benzyl chlorides with terminal alkenes. This reaction, which employs a terminal alkene as an alkenylmetal equivalent, provides rapid, convergent access to substituted allylbenzene derivatives in high yield and with regioselectivity greater than 95:5 in nearly all cases. The reaction is operationally simple, can be carried out on the benchtop with no purification or degassing of solvents or reagents, and requires no exclusion of air or water during setup. Synthesis of the precatalyst is accomplished through a straightforward procedure that employs inexpensive, commercially available reagents, requires no purification steps, and proceeds in high yield.
- Standley, Eric A.,Jamison, Timothy F.
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supporting information
p. 1585 - 1592
(2013/03/14)
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- An acidity scale of tetrafluoroborate salts of phosphonium and iron hydride compounds in [D2]dichIoromethane
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Equilibrium constants (K) for reactions between acids and the conjugate base forms of a number of phosphonium salts, [HPR3][BF4], and iron hydrides, [Fe(CO)3H(PR3)2][BF 4], in CD2Cl2 have been determined by means of 31P and 1H NMR spectroscopy at 20°C. The anchor compound chosen for pKCD2Cl2 determinations was [HPCy 3][BF4] with a pKCD2Cl2 value of 9.7, as assigned by literature convention (Cy: cyclohexyl). A continuous scale of pKCD2Cl2 values covering the range from 9.7 to -3 was created and correlated with the ΔH values reported by Angelici and co-workers and literature pKa values. The pKCD2Cl2 values for 15 other hydride or dihydrogen complexes of the iron group elements and of diethyl ether were also placed on this scale. The crystal structures of [Fe(CO) 3H(PCy2Ph)2][BF4] and [Fe(CO) 3(PCy2Ph)2] revealed that the frans-oriented, bulky, unsymmetrical phosphane ligands distort the equatorial plane of the complexes. The acidity of iron carbonyl hydrides is an important feature of the reactions of iron hydrogenase enzymes.
- Li, Tianshu,Lough, Alan J.,Morris, Robert H.
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p. 3796 - 3803
(2008/02/08)
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- Radical phosphination of organic halides and alkyl imidazole-1- carbothioates
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Taking advantage of a radical-based methodology, mild and chemoselective phosphination reactions of organic halide and alkyl imidazole-1-carbothioates have been developed. The mild reaction conditions allow labile functional groups to survive during the reaction. Copyright
- Sato, Akinori,Yorimitsu, Hideki,Oshima, Koichiro
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p. 4240 - 4241
(2007/10/03)
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- An acidity scale for phosphorus-containing compounds including metal hydrides and dihydrogen complexes in THF: Toward the unification of acidity scales
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More than 70 equilibrium constants K between acids and bases, mainly phosphine derivatives, have been measured in tetrahydrofuran (THF) at 20 °C by 1H and/or 31P NMR. The acids were chosen or newly synthesized in order to cover the wide pK(α)(THF) range of 5-41 versus the anchor compound [HPCy3]BPh4 at 9.7. These pK(α)(THF) values are approximations to absolute, free ion pK(a)(THF) and are obtained by crudely correcting the observed K for 1:1 ion-pairing effects by use of the Fuoss equation. The acid/base compounds include 14 phosphonium/phosphine couples, 17 cationic hydride/neutral hydride couples, 9 neutral polyhydride/anionic hydride couples, 14 dihydrogen/hydride couples, and 4 other nitrogen- and phosphorus-based acids. The effects on pK(α) of the counterions BAr'4- and BF4- vs BPh4- and [K(2,2,2-crypt)]+ versus [K(18-crown-6)+ are found to be minor after correcting for differences in inter-ion distances in the ion-pairs involved. Correlations with v(M-H) noted here for the first time suggest that destabilization of M-H bonding in the conjugate base hydride is an important contributor to hydride acidity. It appears that Re-H bonding in the anions [ReH6(PR3)2- is greatly weakened by small increases in the basicity of PR3, resulting in a large increase in the pK(α) of the conjugate acid ReH7(PR3)2. Correlations with other scales allow an estimate of the pK(α)(THF) values of more than 1000 inorganic and organic acids, 20 carbonyl hydride complexes, 46 cationic hydrides complexes, and dihydrogen gas. Therefore, many new acid-base reactions can be predicted and known reactions explained. THF, with its low dielectric constant, disfavors the ionization of neutral acids HA over HB+ and therefore separate lines are found for pK(α)(THF)(HA) and pK(α)(THF)(HB+) when plotted against pK(a)(DMSO) or pK(a)(MeCN). The crystal structure of [Re(H)2(PMe3)5]BPh4 is reported.
- Abdur-Rashid, Kamaluddin,Fong, Tina P.,Greaves, Bronwyn,Gusev, Dmitry G.,Hinman, Justin G.,Landau, Shaun E.,Lough, Alan J.,Morris, Robert H.
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p. 9155 - 9171
(2007/10/03)
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- Regio- and Stereo-selectivity in the Hydrogenation of Aryl Phosphines by Niobium Aryloxide Compounds
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The sequential hydrogenation of the three aryl rings in PPh3 by the catalyst system /3BunLi occurs with relative rates of 39:28:1; NMR analysis of the PhPCy2 obtained from and shows a predominantly all cis hydrogenation of both aryl rings has occurred.
- Potyen, Mark C.,Rothwell, Ian P.
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p. 849 - 852
(2007/10/02)
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- Hydrogenolysis process
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A process of hydrogenolysis utilizing a new catalyst consisting of a palladium phosphine complex, the phosphien having a pKa greater than or equal to 6, a chlorinated aromatic compound and hydrogen.
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