- An Electron Spin Resonance Study of Alkyl Radical Addition to Diethyl Vinylphosponate
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The irreversible addition of alkyl radicals to diethyl vinylphosphonate to give the α-phosphorylalkyl radicals (1) has been studied by e.s.r. spectroscopy at 233 K in hydrocarbon solvents.The rate constants for addition (kadd) have been determined relative to those (2kAt) for self-reaction of (1) for a series of addenda.The values of 2kAt have been measured in separate kinetic e.s.r. experiments for (1; R = Me) (2.0 x 1E9 dm3mol-1s-1) and (1; R = But) (5.0 x 1E8 dm3mol-1s-1) and thus absolute values of kadd were obtained.The rate constant kadd increases along the series R. = Me. (2.5 x 1E3 dm3mol-1s-1 ) prim. sec. t. (5.9 x 1E4 dm3mol-1s-1) and this order is interpreted in terms of the over-riding importance of polar effects in determining the size of the barrier for addition of these nucleophilic radicals to the electron deficient alkene.R. + H2C=CHP(O)(OEt)2 --> RCH2C.HP(O)(OEt)2 (1)
- Baban, Jehan A.,Roberts, Brian P.
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- Kinetics and mechanism of the reaction of bis-μ-diethylphosphidobis(tetracarbonylmanganese) with tri-n-butylphosphine
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The dinuclear phosphido-bridged manganese complex undergoes thermal CO substitution by PnBu3 in decalin to give nBu3)> and nBu3P)(OC)3Mn(μ-PEt2)2Mn(CO)3(PnBu3)>.A kinetic study of the first CO/PnBu3 exchange indicates that all substitutions for the forward and reverse reactions occur via a dissociative mechanism.The rate of CO dissociation is rather low (k = 6.27 * 10-5 s-1 at 130 deg C), mainly as a consequence of a high activation enthalpy (ΔH* = 165 kJ mol-1).The discriminating ability ofthe resulting coordinatively unsaturated intermediate is only slightly in favour of attack of the more basic PnBu3 compared to CO, as indicated by the values of the competition rate ratio nBu3) = 0.36-0.47>.This behaviour is compared with that of the isostructural chromium complex and discussed in the light of the electronic and structural features related to the metal-metal distance in the two complexes (Mn-Mn = 3.675 Angstroem, Cr-Cr = 2.905 Angstroem, for the μ-PMe2 derivatives).
- Basato, Marino
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- Reaktionen von Phosphanen und Arsanen mit Diselenkomplexen
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The compound Se2 (1) reacts with primary arsanes and phosphanes, and migration of the carbonylmetal fragment Cp'Mn(CO)2 (Cp'=CH3C5H4) from the selenium to the arsenic or phosphorus center occurs.Products of these reactions are diselena-diarsetanes (4) or diselena-diphosphetanes (5).During the reaction of arsanes with 1, arsinidene complexes (2) are obtained in very good yields.Compounds with a P-Se-P unit (6) can be isolated as by-products of the reaction of phosphanes with 1.
- Frank, Lutz-R.,Evertz, Kaspar,Zsolnai, Laszlo,Huttner, Gottfried
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- New insights into the mechanism of reduction of tertiary phosphine oxides by means of phenylsilane
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The mechanism of the reduction of phosphine oxides by PhSiH3 was established on the basis of kinetic measurements and Density Functional Theory (DFT) calculations. In particular, it has been proved that the model reaction between tri-nbutylphosphine oxide and phenylsilane occurs via a nonpolar mechanism. The data presented herein allow prediction and verification of the applicability of the new reduction reagents and conditions for industrially attractive processes.
- Demchuk, Oleg M.,Jasiński, Radomir,Pietrusiewicz, K. Micha?
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Read Online
- 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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- Reductive conversion of phosphoryl P(O) compounds to trivalent organophosphines R3P
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By introducing trimethylsilyl chloride (TMSCl), the pentavalent phosphoryl P(V) compounds such as triphenylphosphine oxides, secondary phosphine oxides etc., were readily converted to the corresponding R2P(OTMS) intermediates, that can further react efficiently with an electrophile R'X or with a nucleophile R'Li to produce the corresponding trivalent phosphines R2PR’. Chiral phosphines could also be obtained stereospecifically by this strategy.
- Zhang, Jian-Qiu,Han, Li-Biao
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supporting information
(2021/02/20)
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- The Trityl-Cation Mediated Phosphine Oxides Reduction
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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.).
- Landais, Yannick,Laye, Claire,Lusseau, Jonathan,Robert, Frédéric
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supporting information
p. 3035 - 3043
(2021/05/10)
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- Reversing Lewis acidity from bismuth to antimony
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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.
- Balasubramaniam, Selvakumar,Jemmis, Eluvathingal D.,Kumar, Sandeep,Sharma, Deepti,Venugopal, Ajay
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supporting information
p. 8889 - 8892
(2021/09/10)
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- Exploring an Umpolung strategy for quaternization of phosphorus
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We propose a new, potentially widely-applicable, Umpolung approach for the synthesis of quaternary phosphonium salts R3PR1 X (X = Cl, Br) from phosphine oxides R3PO. The new organic group R1 is introduced via nucleophilic attack on an intermediate halophosphonium salt using a Grignard reagent R1MgX and replaces the traditional phosphine quaternization approach. Consequently, the new method does not suffer from the limited availability of many parent phosphines and is much faster than standard quaternization.
- Vetter, Anna C.,Nikitin, Kirill,Gilheany, Declan G.
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p. 339 - 342
(2019/03/07)
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- Convergent synthesis of polysubstituted furans via catalytic phosphine mediated multicomponent reactions
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Tri- or tetrasubstituted furans have been prepared from terminal activated olefins and acyl chlorides or anhydrides by a multicomponental convergent synthesis mode. Instead of stoichiometric nBu3P, only catalytic nBu3P or nBu3P=O is needed to furnish the furans in modest to excellent yields with a good functional group tolerance under the aid of reducing agent silane. This synthetic method features a silane-driven catalytic intramolecular Wittig reaction as a key annulation step and represents the first successful application of catalytic Wittig reaction in multicomponent cascade reaction.
- Fan, Xia,Chen, Rongshun,Han, Jie,He, Zhengjie
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supporting information
(2019/12/25)
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- Long sought synthesis of quaternary phosphonium salts from phosphine oxides: Inverse reactivity approach
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Quaternary phosphonium salts (QPS), a key class of organophosphorus compounds, have previously only been available by routes involving nucleophilic phosphorus. We report the realisation of the opposite approach to QPS utilising phosphine oxides as the electrophilic partner and Grignard reagents as nucleophiles. The process is enabled through the crucial intermediacy of the derived halophosphonium salts. The route does not suffer from the slow kinetics and limited availability of many parent phosphines and a broad range of QPS were prepared in excellent yields.
- Vetter, Anna C.,Nikitin, Kirill,Gilheany, Declan G.
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p. 5843 - 5846
(2018/06/13)
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- Br?nsted Acid Promoted Reduction of Tertiary Phosphine Oxides
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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.
- Krachko, Tetiana,Lyaskovskyy, Volodymyr,Lutz, Martin,Lammertsma, Koop,Slootweg, J. Chris
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p. 916 - 921
(2017/08/11)
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- Synthetic method for methyltributylphosphonium iodide
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The invention discloses a synthetic method for methyltributylphosphonium iodide and belongs to the field of preparation of compounds. The synthetic method comprises the steps that firstly, under the protection of nitrogen, chlorobutane and magnesium chips react in a xylene and tetrahydrofuran mixed solvent with methyl iodide as an initiating agent to obtain a butylmagnesium chloride solution; secondly, a product obtained in the first step does not need to be purified and is directly used in the second step after being cooled, in other words, the product obtained in the first step is added with phosphorus trichloride, reacts at a low temperature through stirring and is directly subjected to decompression distillation after the reaction is finished, and tributyl phosphine is obtained with the purity higher than 99%, and the yield in the second step reaches 90.2%; thirdly, home-made tributyl phosphine and methyl iodide react in an ethyl acetate solvent within the temperature range of 35-38 DEG C, and methyltributylphosphonium iodide is obtained, wherein the yield in the third step reaches 93.3%, and purity reaches higher than 99%. According to the method, the reaction temperature is low, the reaction time is short, the solvent is each to recycle, and the yield and the purity of the product are high.
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Paragraph 0014; 0015
(2016/10/09)
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- Highly efficient reduction of tertiary phosphine oxides and sulfides with amine-assisted aluminum hydrides under mild conditions
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Reduction of tertiary phosphine oxides and sulfides into the corresponding phosphines with amine-assisted aluminum hydrides has been studied. The method is characterized by mild conditions, short reaction time, high efficiency, and expanded substrate scope. The new method is an alternative to the currently used methods of reducing phosphine oxides or recycling phosphines engaged in organic reactions.
- Yang, Shuyan,Han, Xinxin,Luo, Minmin,Gao, Jing,Chu, Wenxiang,Ding, Yuqiang
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p. 1156 - 1160
(2015/06/30)
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- Dual [Fe+Phosphine] catalysis: Application in catalytic wittig olefination
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Iron hydride complexes of the general formula P2Fe(NO)CO)H are highly active catalysts for the hydrosilylation of aldehydes or ketones and phosphine oxides. Depending on the solvent, the in situ reduction of the phosphine oxide can be faster than the corresponding hydrosilylation of a carbonyl group. This unusual activity was used within the context of catalytic Wittig olefination. Picture perfect: Iron hydride complexes of the general formula P2Fe(NO)CO)H are highly active catalysts for the hydrosilylation of aldehydes or ketones and phosphine oxides. Depending on the solvent, the in situ reduction of the phosphine oxide can be faster than the corresponding hydrosilylation of a carbonyl group. This unusual activity is used within the context of catalytic Wittig olefination. EWG=Electron-withdrawing group.
- Rommel, Susanne,Belger, Christian,Begouin, Jeanne-Marie,Plietker, Bernd
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p. 1292 - 1301
(2015/04/27)
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- A fast catalytic process of transfer of a phosphorus atom: How folding of the reagent is related to its catalytic activity. a possible correlation with rna behavior
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A simple and very fast process of transfer of a phosphorus atom, performed by a simple molecule acting as catalyst in an almost infinite catalytic cycle is described. The catalyst donates a P atom to a mixture of two different Grignard reagents giving, in a very fast and in a highly selective manner, only one phosphorus-containing compound with an enormous rate enhancement with respect to the corresponding no-catalyzed reaction which gives a final cluttered mixture of many organophosphorus products. The focal factor to explain this highly selective process of P transport lies in the folded structure of the reagent with particular angles around the phosphorus atom which can facilitate the formation of cyclic trigonal bipyramidal pentacoordinated species and then its catalytic activity. In a similar manner, RNA can adopt, in a precise position, a particular three-dimensional structure that might facilitate the formation of pentacoordinated species leading to the catalytic function.
- Baccolini, Graziano,Micheletti, Gabriele
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p. 1254 - 1265
(2014/11/08)
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- Reduction of phosphine oxides to phosphines with the InBr3/TMDS system
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An efficient method for the reduction of phosphine oxide derivatives into their corresponding phosphines is described. The system InBr3/TMDS allows the reduction of different secondary and tertiary phosphine oxides as well as aliphatic and aromatic phosphine oxides.
- Pehlivan, Leyla,Métay, Estelle,Delbrayelle, Dominique,Mignani, Gérard,Lemaire, Marc
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supporting information; experimental part
p. 3151 - 3155
(2012/05/31)
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- PBu3-mediated vinylogous wittig reaction of α-methyl allenoates with aldehydes and mechanistic investigations
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A highly stereoselective PBu3-mediated vinylogous Wittig olefination between α-methyl allenoates and a variety of aldehydes is presented as the first example of a practical and synthetically useful vinylogous Wittig reaction. Mechanistic experiments including deuterium-labeling, intermediate entrapment, and NMR monitoring have been deliberately conducted. On the basis of mechanistic investigations, a reliable mechanism for the vinylogous Wittig reaction is proposed, which features a water/phosphine-coassisted allylic phosphorus ylide 1,3-rearrangement pathway, rather than previous retro-Diels-Alder ones. It is noteworthy that mechanistic findings in this work also provide supportive evidence for typical mechanisms of important phosphine-mediated reactions of allenoates.
- Xu, Silong,Chen, Rongshun,He, Zhengjie
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experimental part
p. 7528 - 7538
(2011/11/29)
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- Solvent, salt and high pressure effects on the rate and equilibrium constants for the formation of tri-n-butylphosphoniumdithiocarboxylate
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Solvent, salt and high pressure effects on the rate and equilibrium constants for the formation of tri-n-butylphosphoniumdithiocarboxylate at 298.2 K are reported. This equilibrium is shifted to the phosphobetaine in polar solvents, salt solutions and under high external pressure. The reaction volume changes dramatically on going from less polar diethyl ether (-69 cm3 mol-1) and tetrahydrofurane (THF) (-66 cm3 mol -1), to more polar acetonitrile (-39 cm3 mol-1) and acetone (-38 cm3 mol-1). Copyright
- Iskhakova, Gulnara G.,Kiselev, Vladimir D.,Van Eldik, Rudi,Zahl, Achim,Shihab, Mehdi S.,Konovalov, Alexander I.
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scheme or table
p. 360 - 365
(2011/11/14)
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- Basic hydrolysis of 1,4-bis(triphenylphosphonio)buta-1,3-diene dihalides
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Basic hydrolysis of 1,4-bis(triphenylphosphonio)buta-1,3-diene dichloride with 10% NaOH gave isomeric 4-diphenylphosphoryl-4-phenylbut-1(2)-enes and 1-diphenylphosphoryl-1-phenylbuta-1,3-diene, the products of anionotropic migration of a phenyl group from the P atom to the -position. Hydrolysis with Na2CO3 afforded only the diene product. In both cases, triphenylphosphine and triphenylphosphine oxide were isolated as secondary products. Dehydrochlorination of 2-chloro-1,4-bis(triphenylphosphonio) but-2-ene dibromide with triphenylphosphine was proposed as a new convenient route to 1,4-bis(triphenylphosphonio)buta-1,3-diene dibromide.
- Ovakimyan,Pogosyan,Movsisyan,Indzhikyan
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experimental part
p. 560 - 564
(2011/02/17)
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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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- A catalytic method for the reduction of secondary and tertiary phosphine oxides
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TMDS has been found to be an efficient hydride source for the reduction of tertiary and secondary phosphine oxides using a catalytic amount of Ti(Oi-Pr)4. All classes of tertiary phosphine oxides, such as triaryl, trialkyl, and diphosphine, were effectively reduced. Georg Thieme Verlag Stuttgart.
- Berthod, Mika?l,Favre-Réguillon, Alain,Mohamad, Jahjah,Mignani, Gérard,Docherty, Gordon,Lemaire, Marc
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p. 1545 - 1548
(2008/02/05)
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- Electrocatalytic eco-efficient functionalization of white phosphorus
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The novel eco-efficient methods to transform white phosphorus into the esters of phosphoric, phosphorous and phosphonic acids, tertiary phosphines and other organophosphorus compounds under conditions of electrochemical catalysis were elaborated. The mechanism of these processes was investigated using the method of cyclic voltammetry and preparative electrolysis.
- Budnikova, Yulia H.,Yakhvarov, Dmitry G.,Sinyashin, Oleg G.
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p. 2416 - 2425
(2007/10/03)
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- A novel mild deprotection method for phosphine-boranes
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Treatment of phosphine-boranes with molecular sieves 4A in a mixture of an ethereal solvent and an alcohol provided deprotected free phosphines in quantitative yields. The phosphines can be obtained by a simple filtration/crystallization procedure in most cases. It should be noted that the current method is successfully applied to the deprotection of a phosphite-borane for the first time.
- Schroeder, Marc,Nozaki, Kyoko,Hiyama, Tamejiro
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p. 1931 - 1932
(2007/10/03)
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- Synthesis, structure and reactivity of sulfur-rich [Fe(L1)(L2)('tpS4')] complexes with rigid [Fe('tpS4'] cores and σ-π co-ligands ('tpS4'2- = 1,2-bis(2-mercaptophenylthio)phenylene(2-); L1 L2 = CO, PR3, NO)
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Optimisation of synthesis and purification steps has made the new ligand 'tpS42- available in preparative amounts. Treatment of FeC12.4H2O with 'tpS4-Li2 or 'tpS4'-Na2 yielded [Fe('tpS4')] (1), which in the solid state and in the absence of co-ligands probably trimerises to give paramagnetic [Fe('tpS4')]3. The [Fe('tpS4')] fragment displays helical coordination of the 'tpS4'2 -ligand and binds σ-π ligands such as CO, NO and phosphanes to give diamagnetic 18-valence-electron complexes of general formula [Fe(L1)(L2) ('tpS4')]. The cis-dicarbonyl complex [Fe(CO)2('tpS4')] (2) is labile and readily dissociates CO to give dinuclear [Fe(CO)('tpS4')]2 (3). Simultaneous coordination of CO and phosphanes yielded [Fe(CO)(PR3)('tpS4')] with R = Me (4), Et (5), Pr (6) and Bu (7), but it proved impossible to obtain analogous complexes with bulky PPh3 or PCy3 ligands. Bis(phosphane) complexes could be obtained only with PMe3 and the bidentate dppe, which yielded [Fe(PMe3)2('tpS4')] (8) and [Fe(dppe)('tpS4')] (11). Alkylphosphanes with longer alkyl substituents, such as PnPr3 and PnBu3, gave the labile derivatives [Fe(PR3)2-('tpS4')] with R = nPr (9) and nBu (10). Complexes 9 and 10 reversibly dissociate one PR3 ligand, yielding diamagnetic [Fe(PR3)('tpS4')] fragments. These findings explain the decisive and hitherto inexplicable influence of PPr3 and PBu3 ligands upon the stabilisation of N2H2 in the diazene complexes [μ-N2H2{Fe(PR3) ('tpS4')}2] with R = Pr, Bu. Treatment of [Fe('tpS4')] (1) or [Fe(CO)('tpS4')]2 (3) with NO or NO+ yielded [Fe(NO)2('tpS4')] (12). The molecular structures of 3, 4, 7 and 8 were determined by X-ray structure analysis. Spectroscopic and structural results indicate that the differences in reactivity between [Fe(L1)(L2)('tpS4')] and homologous [Fe(L1)(L2) ('S4')] complexes can be traced back to subtle electronic and structural effects. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
- Sellmann, Dieter,Blum, David C. F.,Heinemann, Frank W.,Sutterial, Joerg
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p. 418 - 426
(2007/10/03)
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- The influence of the sacrificial anode nature on the mechanism of electrochemical arylation and alkylation of white phosphorus
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The material of the sacrificial anode has a substantial effect on the nature and yield of the target products of electrochemical phosphorylation of organic halides by white phosphorus in the presence of the nickel complexes with 2,2′-bipyridine. The use of the zinc anode results in the products with tricoordinated phosphorus, viz., triorganylphosphines, the reaction on the aluminum anode affords triorganylphosphine oxides, and the presence of Mg 2+ ions in the reaction mixture provides the transformation of white phosphorus into cyclic phosphines (PhP)5.
- Yakhvarov,Budnikova,Tazeev,Sinyashin
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p. 2059 - 2064
(2007/10/03)
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- Organophosphines
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Organophosphines of the formula (R)aP(H)3?a( where R is C1-C20 alkyl, alkenyl, alkaryl or styryl and a is 1, 2, or 3) are produced by (i) reacting a tris(hydroxyorgano)phosphine (THP) with an organic halogen containing compound; (ii) reacting the product of (i) with a base; (iii) removing aldehydes from the product of (ii) and adding an organic phase, followed by distillation or phase-separation to obtain the desired product.
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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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- Reductive desulfurization of organosulfur compounds with sodium in liquid ammonia
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Greater than 95% sulfur removal was observed when dialkyl mono or polysulfides were treated with Na in liquid ammonia. Polycyclic aromatic sulfur heterocycles were only moderately desulfurized under these conditions while phenylthio derivatives gave thiophenol as the major product and dithiophenols as the minor products.
- Yu, Zhengkun,Verkade, John G.
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- Tertiary phosphine ligand-exchange reactions involving the M(Strictly equivalent to)M quadruply bonded complexes M2Cl4L4, where L = PMe3, PEt3, PBun3 or PMe2Ph
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The reactions between M2Cl4L4 complexes and an excess of L or L′ (PMe3, PEt3, PBun3, PMe2Ph or PMePh2) have been studied in [2H8]toluene by 31P-{1H} NMR spectroscopy. The substitutions proceed in a stepwise manner wherein L′ displaces L, except for L′ = Me2PCH2CH2PMe2 (dmpe) which yields Mo2Cl4(dmpe-P)4. No tertiary phosphine in this series is capable of displacing PMe3 from a M2Cl4(PMe3)4 complex but by spin magnetization transfer the degenerate exchange involving Mo2Cl4(PMe3)4 and PMe3 (added in excess) can be detected. The complexes Mo2Cl4(PMe3)4 and Mo2Cl4(PEt3)4 in benzene showed no PMe3 for PEt3 scrambling at +50°C over several days despite the fact that Mo2Cl4(PMe3)4-n(PEt 3)n, where n = 2 or 3, are kinetically inert to ligand redistribution. In the presence of [2H5]pyridine Mo2Cl4(PMe3)4 and Mo2O4(PEt3)4 underwent tertiary phosphine scrambling at 25°C and in neat [2H5]pyridine Mo2Cl4(PMe3)4 revealed the formation of an equilibrium concentration of Mo2Cl4(PMe3)3(py) (py = pyridine) and free PMe3. Under similar conditions Mo2Cl4(PEt3)4 yielded an equilibrium mixture of Mo2Cl4(PEt3)3(py) and Mo2Cl4(PEt3)2(py)2 and free PEt3. From kinetics the ΔH? values are positive in the range +24 to +34 kcal mol-1 and the ΔS? values range from +12 to +28 cal K-1 mol-1. Collectively the data reported are consistent with an interchange dissociative mechanism, Id, wherein M-P bond breaking contributes significantly to the rate-determining step with related values of ΔH? being larger for M = W than M = Mo. The rate dependence on the entering ligand is clearly evident from temperature-dependent studies and leads to varying ΔS? values. The Id mechanism is proposed to involve pre-equilibria between M2Cl4L4 and the entering L′ in an axial site followed by rate-determining M-L displacement. In neat [2H5]pyridine this may be viewed as a solvent-assisted displacement. The present results are discussed in terms of earlier studies from which researchers inferred a simple dissociative process, D, involving M-PR3 bond rupture as the first and rate-determining step.
- Chisholm, Malcolm H.,McInnes, Jacqueline M.
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p. 2735 - 2743
(2007/10/03)
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- Reaction of N-fluoropyridinium salts with Wittig reagents: A novel and convenient approach to symmetric trans-olefins
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N-Fluoropyridinium salts were found to react with Wittig reagents containing electron-withdrawing groups to give olefins in 47-83% yield. The mechanism of this conversion is believed in involve single-electron transfer from Wittig reagent to N-fluoropyridinium cation.
- Kiselyov, Alexander S.
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p. 8951 - 8954
(2007/10/02)
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- Process for preparing organophosphines
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Olefins can be induced to react with phosphines at ambient temperature and pressure to produce organophosphines by free-radical addition. Suitable olefins include C1 to C4 alpha-olefins, cyclic olefins, polycycloalkenyl species, allyl alcohol and esters of vinyl phosphonic acid.
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- Electrochemical studies of nickel complexes containing phosphorus(III) ligands and their related Ziegler catalysts
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All of the data obtained by electrochemical methods involving the mercury electrode, spectrophotometry and conductometry have showed the stepwise formations of a neutral ?-donor-acceptor pentacoordinated NiX2L3 and a cationic tetracoordinated NiL42+, associated with a shift in the dissociation-coordination equilibrium owing to an excessive concentration of the ligand in solutions of the binary systems containing NiII compounds coordinated with acid ligands (X=Cl-, NO3-, acac) and the trivalent phosphorus ligands (L=PBu3, PPh3, P(OEt)3, P(O-i-Pr)3, P(O-s-Bu)3, P(OC6H11), P(OPh)3).The complexes have for the first time been prepared for all the phosphines and phosphites studied.Ni(acac)2 was found to enhance coordination by the phosphines and phosphites in acetonitrile.The value of the semiwave potential shift (ΔE1/2, V) towards less negative potentials depends on the number of ligands present in the inner coordination sphere of metal, and was found to be 200-300 and 800-1300 mV for NiX2L2 and NiL42+, respectively.The electochemical reduction of NiL42+ complexes into the zero-valent nickel isostructural complexes is reversible with values similar to that of the nickel formal potential Ni2+/Ni0 (E1/2=E0=-0.25 V).For the first time, the homogeneous formations of catalitically active complexes have been studied electrochemically in situ with the tricomponent Ziegler-Natta catalytic systems to give stable NiII complexes in toluene solutions of Ni(acac)2--OAC (Ni/P/Al=1/4/4) at T+-.The hydride complexes of divalent nickel HNiL4+ were found to be as catalitically active as the Ni(acac)2-P(OR)3 -AlEt3 (N/P/Al=1/4/4) systems formed in toluene-isopropanol solvent at T=-10 to +25 deg C.The activating effect by the organic phosphorus ligand on the electronic state of Ni has been found for the first time to decrease the energy levels of the boundary orbitals as the coordination sphere becomes saturated with the ligand, thus changing the ligand's environment and configuration of the complex, the degree of alkylation and the degree of stabilization of the catalitically active complexes.In the case of the NiL42+ complexes, the ligand-to-metal charge transfer energies permitted the estimation of the affinity to the nickel electron inherent to the nickel LUMO energy level in the given complex, that energy being similar to HOMO energy in Ni0L4 under the conditions of the reversible electronic process.
- Pozdeeva, A. A.,Dzhemilev, U. M.,Popod'ko, N. R.,Khusnutdinov, R. I.,Zhdanov, S. I.,Tolstikov, G. A.
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p. 205 - 232
(2007/10/02)
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- Synthesis, Characterization, and Thermolytic Behaviour of η3-Allyl(methyl)(tertiary phosphine)palladium(II), and X-Ray Structure of the Cluster 2(μ-Cl)2(μ-dppm)2>*4C4H8O (dppm = Ph2PCH2PPh2)
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Complexes of the type 3-allyl)Me(L)> 3, PPh3, PPh2Me, PPhMe2, or PBun3> have been synthesized and characterized by 1H, 13C n.m.r. and mass spectroscopy.The 3-C3H5)Me(L)> complexes thermally decompose with preferential evolution of ethane rather than but-1-ene, the allylic alkylation product.The participation of the binuclear methyl-bridged intermediate 3-allyl)2(μ-Me)2> (3) is supposed.Indirect support for this is given by the thermolysis of a toluene solution of (3).The effects of phosphines, alkenes, and other additives on the thermolysis products are discussed.The structure of a complex isolated from the 3-allyl)2(μ-Cl)2>-LiMe-Ph2PCH2PPh2 (dppm) reaction system in tetrahydrofuran was revealed by X-ray analysis as two μ-chloro-μ-allyl-dipalladium(I) units bridged by two dppm ligands.
- Hayashi, Yoshihito,Matsumoto, Keiji,Nakamura, Yukio,Isobe, Kiyoshi
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p. 1519 - 1526
(2007/10/02)
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- Ortho-chelated arylrhodium(I) complexes. X-ray structure of RhI[C6H3(CH2NMe2) 2-o,o′-C,N ](COD)
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The reaction of Lin[C6H3(CH2NMe 2)-o-R-o′]n with [RhCl(diene)]2 yields the ortho-chelated arylrhodium(I) complexes Rh[C6H3(CH2NMe 2)-o-R-o′](diene) (R = CH2NMe2, diene = COD (1a) or NBD (1b); diene = COD, R = Me (2) or H (3)). The solid-state structure of 1a was determined by a single-crystal X-ray diffraction study. C20H31N2Rh: triclinic, space group P1, with lattice parameters a = 10.169 (1) ?, b = 13.036 (1) ?, c = 14.688 (2) ?, α = 79.54 (1)°, β = 77.04 (1)°, γ = 79.53°; V = 1845.6 (4) ?3, Z = 4; D(calcd) = 1.448 g cm-3. Refinement with 4696 observed reflections converged at R = 0.0395. The structure of 1a consists of a rhodium(I) center that has a square-planar coordination comprising the two double bonds of COD and a C atom and one of the N atoms of the monoanionic aryl ligand. In solution compounds 1 and 2 exhibit dynamic behavior which involves a reversible dissociation of the Rh-N bond and rotation of the aryl moiety around Rh-C. This process, which generates a highly unsaturated T-shaped 14 electron species, is accompanied by the relief of steric repulsions within the complex. Complex 1 reacts with a range of electrophilic reagents leading to Rh-C bond breakage (HX, X = acac, Cl, Br, OAc, OH, OMe, L-alanyl; MXnLm, SnMe2Br2, NiBr2(PBu3)2, ZrCl4, PdCl2(NCPh)2, HgCl2, PtBr2(COD), and [IrCl(COD)]2). A redox reaction of 1 with AgX (X = OAc, NO3) leads to the formation of RhIIIX2[C6H3(CH2NMe 2)2-o,o′](H2O).
- Van Der Zeijden, Adolphus A. H.,Van Koten, Gerard,Nordemann, Richard A.,Koji?-Prodi?, Biserka,Spek, Anthony L.
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p. 1957 - 1966
(2008/10/08)
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- Catalytic decarbonylation of aldehydes using iron(II) porphyrin complexes, and the crystal structure of (5,10,15,20-tetraphenylporphinato)bis(tri-n-butylphosphine)iron(II)
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The complex (5,10,15,20-tetraphenylporphinato)bis(tri-n-butylphosphine)iron(II), 1, has been isolated in a triclinic crystal form, a = 12.449(3), b = 12.528(2), c = 12.039(2) Angstroem, α = 116.39(1), β = 109.79(1), γ = 98.13(1) deg, Z = 1, space group P1.The structure was solved by conventional heavy atom methods and was refined by full-matrix least-squares procedures to R = 0.060 and Rw = 0.070 for 3551 reflections with I >/= 3 ?(I).The molecule, which has crystallographic 1-Ci symmetry, displays a relatively undistorted pseudo-octahedral coordination geometry with Fe-P = 2.346(1) and Fe-P = 2.346(1) and Fe-N = 1.998(3) and 1.993(3) Angstroem.In CH2Cl2 solution, 1 reacts with CO and aldehydes to generate the carbonyl(phosphine) derivative, and decarbonylation of phenylacetaldehyde to toluene becomes catalytic under an Ar stream.The aldehyde decarbonylations involve radical pathways via carbonyl loss from PhCH2CO.The hydrogen abstraction/initiation reaction probably utilizes trace O2 (and possibly trace water); speculative mechanisms are discussed.
- Belani, Ramesh M.,James, Brian R.,Dolphin, David,Rettig, Steven J.
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p. 2072 - 2078
(2007/10/02)
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- TELLUROPHOSPHONIUM-KATIONEN
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Tellurophosphoranes R3P=Te (R = CH3, i-C3H7, n-C4H9, t-C4H9, N(CH3)2) 1 react with CH3I to give the cations + 2.Te(CH3)2 and R3P are formed on treatment of 2 with LiCH3.
- Kuhn, Norbert,Schumann, Hans
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p. 199 - 202
(2007/10/02)
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- Equilibria for phosphine ligation to ferrous protoporphyrin IX dimethyl ester and related systems in toluene
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Spectrophotometrically derived equilibrium constants for tributylphosphine (PBu3) and tributyl phosphite (P(OBu)3) binding to methylimidazole (MeIm) complexes of iron protoporphyrin IX dimethyl ester (Hm) are reported and compared with new and literature-derived values for ferrous phthalocyanine (FePc) and ferrous dimethylglyoxime (Fe(DMGH)2) analogues. Affinities increase for all three systems in the order MeIm 3 3. Carbon monoxide binding and mutual trans destabilization of P(OBu)3 increases in the order FePc 2 3 have Soret bands at 440 nm. Trans to CO, MeIm is preferred to phosphine ligands. Rate constants for the heme systems estimated from equilibrium data and measured at low temperature are compared with those for FePc and Fe(DMGH)2 analogues. Trends in Keq are most easily understood in terms of rate constants for ligand dissociation, which provide a reliable indicator of coordinate bond energies. Trans effects in hemes and phthalocyanine complexes are similar but differ somewhat from previously established trends in bis(dioxime) complexes of iron.
- Stynes, Dennis V.,Fletcher, David,Chen, Xuening
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p. 3483 - 3488
(2008/10/08)
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- Tertiary alkylphosphine adducts of Mo2(O2CCF3)4 (Mo - 4Mo)
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Mo2(O2CCF3)4 reacts with 2 equiv of PR3 (R = Me, Et, n-Bu) in toluene to give adducts of stoichiometry Mo2(O2CCF3)4·2PR3. These complexes have been characterized by solid-state infrared spectroscopy and variable-temperature 19F and 31P{1H} NMR. A single isomer, with equatorially bound phosphines, is observed in solution at temperatures below ca. -40°C in each case. Previous work on the PMe3 and PEt3 adducts suggested that there were two or more equatorial isomers present in solution at low temperature. The discrepancy between the two studies can be traced to the purity of Mo2(O2CCF3)4, which is usually prepared by metathesis of Mo2(O2CCH3)4 in refluxing trifluoroacetic acid. In our hands, this procedure gives a product contaminated with Mo2(O2C-CF3)3(O2CCH 3). X-ray structural studies on Mo2(O2CCF3)4·2PBu3 show that this complex has a C2h core, which is presumably maintained in solution. The Mo-Mo and Mo-P bond lengths are 2.105 (1) and 2.542 (2) A?, respectively. The differences in solution behavior between homologous M2(O2CCF3)4·2PR3 complexes (M = Mo, W) are discussed and correlated with M-P bond strengths. Phosphine-exchange reactions are used to generate the mixed-phosphine equatorial adducts M2(O2CCF3)4·PEt 3·PBu3 (M = Mo, W) in solution. The electronic absorption spectra of M2(O2CCF3)4·2PMe3 (M = Mo, W) are reported and the δ → δ*, 1Ag → 1Bu transitions are assigned and discussed. Crystal data (at -125°C) for Mo2(O2CCF3)4·2PBu3 are as follows: monoclinic space group I2/a, a = 19.390 (10) A?, b = 10.414 (4) A?, c = 21.790 (11) A?, β = 94.64 (4)°, V = 4385.58 A?3, Z = 4, dcalcd = 1.586 g cm-3.
- Santure,Sattelberger
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p. 3477 - 3482
(2008/10/08)
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- Process for preparing tertiary phosphines
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Tertiary phosphine oxides, such as triphenylphosphine oxide, are reduced to the corresponding phosphines in the presence of a trialkylaluminum/trialkyl borate reducing agent.
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- A GENERAL SYNTHESIS OF OPTICALLY ACTIVE PHOSPHINES, PHOSPHINITES AND THIOPHOSPHINITES FROM ALKYLTHIO(ALKYLSELENO)PHOSPHONIUM SALTS AND TRIS(DIMETHYLAMINO)PHOSPHINE AS A THIOPHILIC AGENT
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Tris(dimethylamino)phosphine was found to be a suitable thiophilic reagent which converts optically active alkylthio(alkylseleno)phosphonium salts into chiral tertiary phosphines and phosphonites with a high stereoselectivity.The first synthesis of optically active thiophosphinites from bis(alkylthio)phosphonium salts and tris(dimethylamino)phosphine is also reported.
- Omelanczuk, J.,Mikolajczyk, M.
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p. 2493 - 2496
(2007/10/02)
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- 16-Amino-18,19,20-trinor-prostaglandin derivatives, and acid addition salts
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The invention relates to new 16-amino-18,19,20-trinor-prostaglandin derivatives of general formula I, having at C-17 a substituted or unsubstituted phenyl group, wherein C-15 and C-16 may have either S or R configuration, Y stands for a hydrogen atom or a lower alkyl group, W stands for a hydrogen atom, halogen atom, hydroxy group, lower alkyl or alkoxy group, and their acid addition salts. These compounds can be prepared by removing the ester group and the p-nitrobenzyloxycarbonyl protective group of a 9α,11α,15-trihydroxy-16-p-nitrobenzyloxycarbonylamido-17-phenyl-5-cis,13-trans-18,19,20-trinor-prostadienoic acid derivative of general formula XII--wherein C-15 and C-16 may have either S or R configuration, W is as defined above, and Y stands for a lower alkyl group--in an optional sequence with the limitation that in those compounds of general formula I where W is as defined above and Y stands for a lower alkyl group, solely the p-nitrobenzyloxycarbonyl group is removed, and the resulting product of general formula I is optionally converted with an organic or inorganic acid into a salt. The new prostaglandin derivatives of the invention have valuable therapeutical properties, and can be applied in cattle raising for estrus and birth synchronization, furthermore in the veterinary praxis for the treatment of sterility, chronic endometritis and pyometry.
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- Process for producing 2-(2'-methyl-1'-propenyl)-4-methyltetrahydropyran
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Rose oxide, which is an important olfactive compound valuable in the art of perfumery, is advantageously produced from citronellol through a novel synthetic route comprising (1) anodic alkoxylation of citronellol using as a supporting electrolyte an alkali metal aromatic sulfonate, (2) dealkoxylation of the resulting 2,6-dimethyl-3-alkoxyoct-1-en-8-ol in the presence of a palladium or nickel complex, and then (3) cyclization of the resulting dehydrocitronellol in the presence of an acid.
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- 15-Deoxy-16-hydroxy-16-vinyl or cyclopropyl prostan-1-ols of the E, A and F series
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This disclosure describes novel 15-deoxy-16 hydroxy-16-substituted prostanoic acid analogs in which the C-1 carboxyl is replaced by a primary alcohol and carboxylic acid esters, carbonates and carbomates thereof. The prostanoic carbinols and carboxylic acid esters thereof described herein have utility as bronchodilators as hypotensive agents, and as agents for the control of excessive gastric secretion.
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- LIGAND DISSOCIATION FROM MONO-SUBSTITUTED DERIVATIVES OF HEXACARBONYLCHROMIUM (Cr(CO)5L, L = P(C6H5)3, P(C4H9)3, P(OCH3)3, P(OC6H5)3, AND As(C6H5)3)
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The rates of dissociation of the unique ligand from Cr(CO)5L have been determined for L = P(C6H5)3, P(OC6H5)3, P(OCH3)3, and As(C6H5)3 by reaction with CO.The reactions were investigated from 80-140 deg C and activation parameters were determined.The rate
- Wovkulich, Michael J.,Atwood, Jim D.
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- Selective formation of ethanol from methanol, hydrogen and carbon monoxide
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A process for the selective formation of ethanol which comprises contacting methanol, hydrogen and carbon monoxide with a catalyst system comprising cobalt acetylacetonate, a tertiary organo Group V A compound of the periodic Table, a first promoter comprising an iodine compound and a second promoter comprising a ruthenium compound.
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- Structural studies of derivatives of methinyltricobalt enneacarbonyls. I. The crystal structure of CH3CCo3(CO)8P(C6H5) 3
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The crystal and molecular structure of CH3CCo3(CO)8P(C6H5) 3 has been determined by three-dimensional X-ray analysis. Crystals of the compound are monoclinic, space group C2h5-P21/c, with four molecules in a cell of dimensions a = 12.19 (2), b = 16.11 (2), c = 17.19 (4) ?; β = 120.0 (1)°. X-Ray data were collected by conventional film techniques using Co Kα radiation, the intensities of 2189 independent reflections being measured photometrically. The structure has been refined isotropically by modified full-matrix least-squares techniques to a conventional R factor of 0.099. The monomeric molecular structure closely resembles the parent compound CH3CCo3(CO)9 being based on a Co3 triangle. The P(C6H5)3 unit has simply replaced one of the equatorial carbonyl groups, causing small distortions in the remainder of the molecule. Co-Co bond lengths are in the range 2.490-2.510 (6) ?.
- Brice,Penfold,Robinson, Ward T.,Taylor, Susan R.
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p. 362 - 367
(2008/10/08)
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