18803-09-3Relevant academic research and scientific papers
A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics
Taylor, Nicholas P.,Gonzalez, Jorge A.,Nichol, Gary S.,García-Domínguez, Andrés,Leach, Andrew G.,Lloyd-Jones, Guy C.
, p. 721 - 729 (2022/01/04)
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.
Versatile Visible-Light-Driven Synthesis of Asymmetrical Phosphines and Phosphonium Salts
Arockiam, Percia Beatrice,Lennert, Ulrich,Graf, Christina,Rothfelder, Robin,Scott, Daniel J.,Fischer, Tillmann G.,Zeitler, Kirsten,Wolf, Robert
supporting information, p. 16374 - 16382 (2020/11/03)
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.
Ligand-free palladium catalyzed phosphorylation of aryl iodides
Nowrouzi, Najmeh,Keshtgar, Saba,Bahman Jahromi, Enayatollah
, p. 348 - 350 (2016/01/12)
A reusable ligand-free palladium catalyzed phosphorylation of aryl iodides using PdCl2/tetrabutylammonium bromide is described. Functionalized triarylphosphines were obtained in good to excellent yields in the absence of external reductants and supporting ligands.
Towards the efficient development of homogeneous catalytic transformation to γ-valerolactone from biomass-derived platform chemicals
Dutta Chowdhury, Abhishek,Jackstell, Ralf,Beller, Matthias
, p. 3360 - 3365 (2015/04/16)
Recent efforts focused on the production of selected chemicals from biomass as an effective approach to replace fossil feedstocks. Among them, transformation of the biogenic platform molecule levulinic acid to γ-valerolactone has been an extensively studied reaction. Although this transformation can be achieved by heterogeneous catalysis, there exists also a strong interest for effective homogeneous catalysis that can operate selectively under milder and sustainable conditions. Herein, we report the utilization of various triphos-analogue ligands that in the presence of Ru(acac)3 (acac=acetylacetonate) lead to highly efficient γ-valerolactone production (yield up to 95 %). Excellent catalyst turnover numbers (up to 75 855) and turnover frequencies (up to 1382 h-1) were accomplished. Practically sustainable in every way: The practical production of γ-valerolactone (GVL) is described from the biomass-derived platform chemicals methyl levulinate and levulinic acid using three different ruthenium-triphos-based catalyst systems under optimized reaction conditions. acac=Acetylacetonate, TON=turnover number, TOF=turnover frequency.
Phosphinodi(benzylsilane) PhP{(o -C6H4CH 2)SiMe2H}2: A versatile pSi 2Hx pincer-type ligand at ruthenium
Montiel-Palma, Virginia,Munoz-Hernandez, Miguel A.,Cuevas-Chavez, Cynthia A.,Vendier, Laure,Grellier, Mary,Sabo-Etienne, Sylviane
, p. 9798 - 9806 (2013/09/23)
The synthesis of the new phosphinodi(benzylsilane) compound PhP{(o-C 6H4CH2)SiMe2H}2 (1) is achieved in a one-pot reaction from the corresponding phenylbis(o- tolylphosphine). Compound 1 acts as a pincer-type ligand capable of adopting different coordination modes at Ru through different extents of Si-H bond activation as demonstrated by a combination of X-ray diffraction analysis, density functional theory calculations, and multinuclear NMR spectroscopy. Reaction of 1 with RuH2(H2)2(PCy 3)2 (2) yields quantitatively [RuH2{[η 2-(HSiMe2)-CH2-o-C6H 4]2PPh}(PCy3)] (3), a complex stabilized by two rare high order ε-agostic Si-H bonds and involved in terminal hydride/η2-Si-H exchange processes. A small free energy of reaction (ΔrG298 = +16.9 kJ mol-1) was computed for dihydrogen loss from 3 with concomitant formation of the 16-electron species [RuH{[η2-(HSiMe2)-CH 2-o-C6H4]PPh[CH2-o-C 6H4SiMe2]}(PCy3)] (4). Complex 4 features an unprecedented 29Si NMR decoalescence process. The dehydrogenation process is fully reversible under standard conditions (1 bar, 298 K).
Effects of phosphorus substituents on reactions of α- alkoxyphosphonium salts with nucleophiles
Goto, Akihiro,Otake, Kazuki,Kubo, Ozora,Sawama, Yoshinari,Maegawa, Tomohiro,Fujioka, Hiromichi
supporting information, p. 11423 - 11432 (2012/11/07)
The effects of phosphorus substituents on the reactivity of α-alkoxyphosphonium salts with nucleophiles has been explored. Reactions of α-alkoxyphosphonium salts, prepared from various acetals and tris(o-tolyl)phosphine, with a variety of nucleophiles proceeded efficiently. These processes represent the first examples of high-yielding nucleophilic substitution reactions of α-alkoxyphosphonium salts. The reactivity of these salts was determined by a balance between steric and electronic factors, respectively, represented by cone angles θ and CO stretching frequencies ν (steric and electronic parameters, respectively). In addition, a novel reaction of α-alkoxyphosphonium salts derived from Ph3P with Grignard reagents was observed to take place in the presence of O2 to afford alcohols in good yields. A radical mechanism is proposed for this process that has gained support from isotope-labeling and radical-inhibition experiments. A dramatic change in the reactivity of an α-alkoxyphosphonium salt toward nucleophiles is observed due to the steric and electronic nature of the phosphine substituents. By changing the type of phosphorus substituents, the reaction pathway can be controlled to proceed selectively by substitution or a new radical reaction (see scheme; OTf=trifluoromethansulfonate, TMS=trimethylsilyl, o-tol=tolyl). Copyright
Biphasic aqueous organometallic catalysis promoted by cyclodextrins: How to design the water-soluble phenylphosphane to avoid interaction with cyclodextrin
Ferreira, Michel,Bricout, Herve,Sayede, Adlane,Ponchel, Anne,Fourmentin, Sophie,Tilloy, Sebastien,Monflier, Eric
experimental part, p. 609 - 618 (2009/04/21)
The ability of cyclodextrin to interact with meta-trisulfonated triphenylphosphane derivatives bearing one or two methyl (or methoxy) groups on the aromatic ring has been investigated by NMR and UV-vis spectroscopy. In the case of native β-cyclodextrin (β-CD), the presence of one methyl or methoxy group in the ortho-position on each aromatic ring is necessary to hamper the formation of an inclusion complex between the β-CD and meta-trisulfonated triphenylphosphane derivatives. In the case of methylated β-CD, the formation of an inclusion complex is only observed when the meta-trisulfonated triphenylphosphane contains a methyl group in the para-position. The poor affinity of methylated β-CD towards modified trisulfonated triphenylphosphanes was attributed to the steric hindrance generated by the methyl groups on the CD secondary face. The absence or presence of an interaction between phosphanes and methylated β-CD was also confirmed by catalytic experiments. Thus, the phosphanes that do not interact with the methylated CD were the most efficient mass-transfer promoters in an aqueous biphasic palladium-catalyzed Tsuji-Trost reaction.
PHOSPHORORGANISCHE VERBINDUNGEN 101. TERTIAERE PHOSPHINE MIT ORTHOALKOXYPHENYL-GRUPPEN. Synthese und Eigenschaften
Horner, L.,Simons, G.
, p. 189 - 210 (2007/10/02)
Alkylphenylethers, ortho-lithiated in good yields, are transformed according to scheme (1) to the triarylphosphines ArPPh2, Ar2PPh and Ar3P (Ar contains in all cases an ortho-alkoxy group) (Table 1.).Hydroquinonedialkylethers can be lithiated twice, forming the compounds 102 and 103.Table 2 summarizes some arylalkylethers (71 - 101) which were lithiated; table 7 presents 12 new arylalkylethers.The syntheses of triarylphosphines with one or two bulky groups (105 - 110) and of triarylphosphines with one or two 3,4-dialkoxyphenyl groups (111 - 114) are reported.The 31P-spectra of the compounds prepared are discussed with respect to the validity of the Tolman-rule.
