- Rapid Metal-Free Formation of Free Phosphines from Phosphine Oxides
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A rapid method for the reduction of secondary phosphine oxides under mild conditions has been developed, allowing simple isolation of the corresponding free phosphines. The methodology involves the use of pinacol borane (HBpin) to effect the reduction while circumventing the formation of a phosphine borane adduct, as is usually the case with various other commonly used borane reducing agents such as borane tetrahydrofuran complex (BH3?THF) and borane dimethyl sulfide complex (BH3?SMe2). In addition, this methodology requires only a small excess of reducing agent and therefore compares favourably not just with other borane reductants that do not require a metal co-catalyst, but also with silane and aluminium based reagents. (Figure presented.).
- Provis-Evans, Cei B.,Emanuelsson, Emma A. C.,Webster, Ruth L.
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- Hydrogen/Halogen Exchange of Phosphines for the Rapid Formation of Cyclopolyphosphines
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The hydrogen/halogen exchange of phosphines has been exploited to establish a truly useable substrate scope and straightforward methodology for the formation of cyclopolyphosphines. Starting from a single dichlorophosphine, a sacrificial proton "donor phosphine"makes the rapid, mild synthesis of cyclopolyphosphines possible: reactions are complete within 10 min at room temperature. Novel (aryl)cyclopentaphosphines (ArP)5 have been formed in good conversion, with the crystal structures presented. The use of catalytic quantities of iron(III) acetylacetonate provides significant improvements in conversion in the context of diphosphine (Ar2P)2 and alkyl-substituted cyclotetra- or cyclopentaphosphine ((AlkylP)n, where n = 4 or 5) formation. Both iron-free and iron-mediated reactions show high levels of selectivity for one specific ring size. Finally, investigations into the reactivity of Fe(acac)3 suggest that the iron species is acting as a sink for the hydrochloric acid byproduct of the reaction.
- Barrett, Adam N.,Woof, Callum R.,Goult, Christopher A.,Gasperini, Danila,Mahon, Mary F.,Webster, Ruth L.
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supporting information
p. 16826 - 16833
(2021/11/04)
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- Iminophosphanes: Synthesis, Rhodium Complexes, and Ruthenium(II)-Catalyzed Hydration of Nitriles
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Highly stable iminophosphanes, obtained from alkylating nitriles and reaction of the resulting nitrilium ions with secondary phosphanes, were explored as tunable P-monodentate and 1,3-P,N bidentate ligands in rhodium complexes. X-ray crystal structures ar
- Rong, Mark K.,Van Duin, Koen,Van Dijk, Tom,De Pater, Jeroen J. M.,Deelman, Berth-Jan,Nieger, Martin,Ehlers,Slootweg, J. Chris,Lammertsma, Koop
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supporting information
p. 1079 - 1090
(2017/04/21)
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- Facile, Catalytic Dehydrocoupling of Phosphines Using β-Diketiminate Iron(II) Complexes
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Catalytic dehydrocoupling of primary and secondary phosphines has been achieved for the first time using an iron pre-catalyst. The reaction proceeds under mild reaction conditions and is successful with a range of diarylphosphines. A proton acceptor is not needed for the transformation to take place, but addition of 1-hexene does allow for turnover at 50°C. The catalytic system developed also facilitates the dehydrocoupling of phenylphosphane and dicyclohexylphosphane. A change in solvent switches off dehydrocoupling to allow hydrophosphination of alkenes.
- King, Andrew K.,Buchard, Antoine,Mahon, Mary F.,Webster, Ruth L.
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supporting information
p. 15960 - 15963
(2015/11/03)
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- Selective dehydrocoupling of phosphines by lithium chloride carbenoids
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The development of a simple, transition-metal-free approach for the formation of phosphorus-phosphorus bonds through dehydrocoupling of phosphines is presented. The reaction is mediated by electronically stabilized lithium chloride carbenoids and affords a variety of different diphosphines under mild reaction conditions. The developed protocol is simple and highly efficient and allows the isolation of novel functionalized diphosphines in high yields.
- Molitor, Sebastian,Becker, Julia,Gessner, Viktoria H.
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p. 15517 - 15520
(2014/12/12)
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- Convenient methods for the synthesis of a library of hemilabile phosphines
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A series of novel functionalized phosphines of hemilabile character, R 2P(CH2)nZ, have been prepared from diarylphosphines using several synthetic methodologies. The synthetic methods include the alkylation of lithium diar
- Jimenez, M. Victoria,Perez-Torrente, Jesus J.,Bartolome, M. Isabel,Oro, Luis A.
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body text
p. 1916 - 1922
(2009/12/28)
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- A superior method for the reduction of secondary phosphine oxides
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(Chemical Equation Presented) Diisobutylaluminum hydride (DIBAL-H) and triisobutylaluminum have been found to be outstanding reductants for secondary phosphine oxides (SPOs). All classes of SPOs can be readily reduced, including diaryl, arylalkyl, and dialkyl members. Many SPOs can now be reduced at cryogenic temperatures, and conditions for preservation of reducible functional groups have been found. Even the most electron-rich and sterically hindered phosphine oxides can be reduced in a few hours at 50-70°C. This new reduction has distinct advantages over existing technologies.
- Busacca, Carl A.,Lorenz, Jon C.,Grinberg, Nelu,Haddad, Nizar,Hrapchak, Matt,Latli, Bachir,Lee, Heewon,Sabila, Paul,Saha, Anjan,Sarvestani, Max,Shen, Sherry,Varsolona, Richard,Wei, Xudong,Senanayake, Chris H.
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p. 4277 - 4280
(2007/10/03)
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- A METHOD FOR GENERATING SECONDARY PHOSPHINES
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This invention provides a method for generating secondary phosphines from secondary phosphine oxides in the presence of a reducing agent, such as diisobutylaluminum hydride (DIBAL-H), triisobutyldialuminoxane, triisobutylaluminum, tetraisobutyldialuminoxane, or another reducing agent comprising: (i) an R1R2AIH moiety, wherein R1 and R2 are each an alkyl species or oxygen, and wherein at least one of R1 or R2 comprises at least 2 carbon atoms, or (ii) an R1R2R3AI moiety, wherein R1, R2, and R3 are not hydrogen, and wherein at least one of R1, R2, and R3 is an alkyl species comprising a β-hydrogen, not including triethylaluminum. Preferred reducing agents for the present invention include: diisobutylaluminum hydride, triisobutyldialiuminoxane, triisobutylaluminum, tetraisobutyldialuminoxane, and combinations thereof.
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Page/Page column 12-13
(2008/06/13)
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- Reductive cleavage of the carbon-phosphorus bond with alkali metals. I. Cleavage of functionalised triphenylphosphines; formation of secondary and primary phosphines
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The reductive cleavage reaction of functionalised triphenylphosphines 1-34 with Na/NH3 and Li/THF depends strongly on the nature of the functionality and on the reducing agent. No reduction occurs with 11, 24, 30, 31 and 32 in Na/NH3.Compounds 3, 4, 5, 10, 12, 13, 15, 19, 23, 25, 26 and 27 cleave to give the secondary phosphide in high yield with Na/NH3, whereas 2, 7 and 9 give a high yield with Li/THF.Reduction occurs but cleavage is poor with 6, 7, 14, 29 and 34 and Na/NH3, or with 11 and Li/THF.Primary ortho-functionalised phenyl phosphines are obtained by a double cleavage reduction from 2, 5, 12, 25, 26 and 27 with Na/NH3.This unprecedented reaction proceeds via the secondary phosphine, which is formed by protonation of the corresponding phosphide with NH3.It occurs when the aryl group contains a strongly electron-donating substituent.Multiple cleavage of aryl groups with extended ? systems occurs with 7 and 34 when they are made to react with Li/THF.Halogens are cleaved from the phenyl group (16, 17, 18, 28 and 33, with Na/NH3), whereas SCH3 groups are converted to the corresponding mercapto group (20, 21 and 22).Birch reduction (2 and 10) can take place in NH3 but not in the aprotic solvent THF; it occurs only when other reactions are slow.Sodium amide is obtained via reaction of 8 in Na/NH3.Restricted Hartree-Fock calculations were carried out for a number of substituted phenylphosphines.From the correlation between the energies and coefficients of the LUMO (always an aryl ?* orbital) and the experimental cleavage data, it was concluded that there are three requirements for successful cleavage.The LUMO energy should be neither too high (no reduction) nor too low (radical anion too stable) and, further, the coefficient of the LUMO on the carbon attached to phosphorus must be large.
- Budzelaar, Peter H. M.,Doorn, Johannes A. van,Meijboom, Nico
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p. 420 - 432
(2007/10/02)
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