1486-28-8Relevant academic research and scientific papers
Br?nsted Acid Promoted Reduction of Tertiary Phosphine Oxides
Krachko, Tetiana,Lyaskovskyy, Volodymyr,Lutz, Martin,Lammertsma, Koop,Slootweg, J. Chris
, p. 916 - 921 (2017)
Recently, Br?nsted acids, such as phosphoric acids, carboxylic acids, and triflic acid, were found to catalyze the reduction of phosphine oxides to the corresponding phosphines. In this study, we fully characterize the HCl, HOTf, and Me2SiHOTf adducts of triphenylphosphine oxide and find that the thermally stable adduct Ph3POH+OTf– is efficiently converted into triphenylphosphine at 100 °C in the presence of readily available hydrosiloxanes. Under the same reaction conditions, also Ph3POSiMe2H+OTf– selectively affords triphenylphosphine indicating that silylated phosphine oxides are likely intermediates in this process.
Ethylene Tetramerization Catalysis: Effects of Aluminum-Induced Isomerization of PNP to PPN Ligands
Lifschitz, Alejo M.,Hirscher, Nathanael A.,Lee, Heui Beom,Buss, Joshua A.,Agapie, Theodor
, p. 1640 - 1648 (2017)
Diphosphinoamines (PNP) are commonly used to support Cr-catalyzed ethylene trimerization and tetramerization. Although isomerization of PNP to a PPN (iminobisphosphine) species has been established, such reactivity has not been studied in detail in the context of Cr-based selective ethylene oligomerization catalysis. Herein, we show that precursors that are stable as PNP frameworks can isomerize to PPN species in the presence of chlorinated aluminum activators relevant to ethylene oligomerization catalysis. Isomerization changes the pattern of reactivity of the ligands, making them more susceptible to nucleophilic attack by alkyl groups, resulting in a variety of degradation products. The isomerization-mediated degradation of PNP ligands leads to the formation of unwanted polymerization catalysts in ethylene tetramerization systems, thus providing insight into the formation of Cr species that affect the overall selectivity and activity values. For example, independently prepared [R2PNR]- leads to potent Cr polymerization catalysts. The susceptibility for isomerization is dependent on the nature of the N-substituent of the PNP precursor. Electron donating N-substituent i-Pr, which disfavors the PPN isomer compared to p-tolyl, and minimization of water contamination correlate with higher oligomerization activity and lower polymer byproducts. More broadly, the present study demonstrates the significant impact that Al-activators can have on the structure and behavior of the supporting ligand leading to detrimental reactivity.
Palladium-Catalyzed Cleavage of P-C Bonds In Quaternary Phosphonium Salts and Its Applications to Organic Synthesis
Sakamoto, Masato,Shimizu, Isao,Yamamoto, Akio
, p. 1101 - 1102 (1995)
Phosphonium salts, PPh4I and PMePh3I, oxidatively add to Pd(methyl acrylate)(PMePh2)2 to give trans- in moderate yields with cleavage of the P-phenyl bond.Conversely thermolysis of trans-PdPhIL2(L = PMePh2 and PPh3) reductively eliminates PMePh3I and PPh4I, respectively.Application of the P-C bond cleavage process in phosphonium salts to olefination, carbonylation and hydrogenation reactions has been explored.
Dimethylsulfonium methylide in methylation of silylphosphines
Veits,Chuchuryukin,Neganova
, p. 1790 - 1792 (2002)
Selective monodesilylation of bissilylated alkyl- or arylphosphines under the action of dimethylsulfonium methylide and the subsequent methylation of the resulting silyl phosphides with the sulfonium salt offers a convenient route to difficultly accessible monosilylated secondary methylalkyl(aryl)phosphines.
Alane - A novel way to reduce phosphine oxides
Griffin, Sara,Heath, Lucy,Wyatt, Paul
, p. 4405 - 4406 (1998)
Phosphine oxides may be reduced to phosphines in excellent yield using alane - AIH3. An aqueous workup is not required.
Preparation and properties of a series of structurally diverse aluminium hydrides supported by β-diketiminate and bis(amide) ligands
Nako, Adi E.,Gates, Sarah J.,White, Andrew J.P.,Crimmin, Mark R.
, p. 15199 - 15206 (2013)
The synthesis of a diverse series of hydride complexes of aluminium coordinated by N,N'-chelating ligands is reported. Reaction of [{2,6- iPr2C6H3}NC(Me)CHC(Me)N(H)CH 2CH2NMe2] with either LiAlH4 or Me3N·AlH3 allows isolation of the corresponding five-coordinate aluminium dihydride [κ3-{(2,6- iPr2C6H3)NC(Me)CHC(Me)NCH 2CH2NMe2}AlH2] (2). The latter complex demonstrates trigonal bipyramidal geometry in the solid-state. Correlation of solid and n-hexane solution infrared spectroscopy data reveals that this coordination is retained in solution. To evaluate the observed coordination geometry, the dissociation of the pendant ligand of 2 was investigated by DFT methods conducted with the M06-2X functional and a hybrid 6,31G+(d,p)/Lanl2DZ basis-set. Reaction of Me3N·AlH 3 with both N,N′-bis(di-iso-propylphenyl)ethylenediamine and N,N'-bis(mesityl)ethylenediamine gave [{κ2-(ArNCH 2)2}AlH(NMe3)] (Ar = Mes, 3a; Ar = 2,6-di-iso-propylphenyl, 3b) in moderate yields. Removal of NMe3 from 3b by heating under dynamic vacuum allowed the isolation of cis-[AlH{μ-N(Ar)CH2CH2N(Ar)}] (Ar = 2,6-di-iso-propylphenyl, cis-4b2) as a single diastereomer following crystallization. DFT studies in combination with infrared and NMR spectroscopy and single crystal X-ray diffraction data provide a weight of evidence consistent with the robust dimeric structure of cis-4b2 remaining intact in solution. An unusual reaction in which the aluminium dihydride, [κ2-{(2,6-Me2C6H3NHCH 2)2CH}AlH2], promotes the P-C bond cleavage of Ph3PCH2 is also reported.
The Trityl-Cation Mediated Phosphine Oxides Reduction
Landais, Yannick,Laye, Claire,Lusseau, Jonathan,Robert, Frédéric
supporting information, p. 3035 - 3043 (2021/05/10)
Reduction of phosphine oxides into the corresponding phosphines using PhSiH3 as a reducing agent and Ph3C+[B(C6F5)4]? as an initiator is described. The process is highly efficient, reducing a broad range of secondary and tertiary alkyl and arylphosphines, bearing various functional groups in generally good yields. The reaction is believed to proceed through the generation of a silyl cation, which reaction with the phosphine oxide provides a phosphonium salt, further reduced by the silane to afford the desired phosphine along with siloxanes. (Figure presented.).
Reversing Lewis acidity from bismuth to antimony
Balasubramaniam, Selvakumar,Jemmis, Eluvathingal D.,Kumar, Sandeep,Sharma, Deepti,Venugopal, Ajay
supporting information, p. 8889 - 8892 (2021/09/10)
Investigations on the boundaries between the neutral and cationic models of (Mesityl)2EX (E = Sb, Bi and X = Cl?, OTf?) have facilitated reversing the Lewis acidity from bismuth to antimony. We use this concept to demonstrate a higher efficiency of (Mesityl)2SbOTf(Mesityl)2BiOTf in the catalytic reduction of phosphine oxides to phosphines. The experiments supported with computations described herein will find use in designing new Lewis acids relevant to catalysis.
A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics
García-Domínguez, Andrés,Gonzalez, Jorge A.,Leach, Andrew G.,Lloyd-Jones, Guy C.,Nichol, Gary S.,Taylor, Nicholas P.
supporting information, (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.
Reduction of tertiary phosphine oxides to phosphine-boranes using Ti(Oi-Pr)4/BH3-THF
Sowa, Sylwia,Pietrusiewicz, K. Micha?
, (2021/03/17)
A new method for reduction of tertiary phosphine oxides leading to the formation of tertiary phosphine-boranes has been developed. The BH3-THF/Ti(Oi-Pr)4 reducing system enables conversion of triaryl, diarylalkyl and trialkylphosphine oxides directly to their borane analogues in good to high yields. In contrast to the previously reported protocols, the presence of activating groups in the structure of starting material is not necessary for the reaction to occur. The reaction is highly stereoselective and proceeds with predominant retention of configuration at the phosphorus atom. A plausible mechanism of reduction of the P[dbnd]O bond by BH3-THF/Ti(Oi-Pr)4 has been proposed.
