- Complexation and Versatile Reactivity of a Highly Lewis Acidic Cationic Mg Complex with Alkynes and Phosphines
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[(BDI)Mg+][B(C6F5)4?] (1; BDI=CH[C(CH3)NDipp]2; Dipp=2,6-diisopropylphenyl) was prepared by reaction of (BDI)MgnPr with [Ph3C+][B(C6F5)4?]. Addition of 3-hexyne gave [(BDI)Mg+?(EtC≡CEt)][B(C6F5)4?]. Single-crystal X-ray analysis, NMR investigations, Raman spectra, and DFT calculations indicate a significant Mg-alkyne interaction. Addition of the terminal alkynes PhC≡CH or Me3SiC≡CH led to alkyne deprotonation by the BDI ligand to give [(BDI-H)Mg+(C≡CPh)]2?2 [B(C6F5)4?] (2, 70 %) and [(BDI-H)Mg+(C≡CSiMe3)]2?2 [B(C6F5)4?] (3, 63 %). Addition of internal alkynes PhC≡CPh or PhC≡CMe led to [4+2] cycloadditions with the BDI ligand to give {Mg+C(Ph)=C(Ph)C[C(Me)=NDipp]2}2? 2 [B(C6F5)4?] (4, 53 %) and {Mg+C(Ph)=C(Me)C[C(Me)=NDipp]2}2?2 [B(C6F5)4?] (5, 73 %), in which the Mg center is N,N,C-chelated. The (BDI)Mg+ cation can be viewed as an intramolecular frustrated Lewis pair (FLP) with a Lewis acidic site (Mg) and a Lewis (or Br?nsted) basic site (BDI). Reaction of [(BDI)Mg+][B(C6F5)4?] (1) with a range of phosphines varying in bulk and donor strength generated [(BDI)Mg+?PPh3][B(C6F5)4?] (6), [(BDI)Mg+?PCy3][B(C6F5)4?] (7), and [(BDI)Mg+? PtBu3][B(C6F5)4?] (8). The bulkier phosphine PMes3 (Mes=mesityl) did not show any interaction. Combinations of [(BDI)Mg+][B(C6F5)4?] and phosphines did not result in addition to the triple bond in 3-hexyne, but during the screening process it was discovered that the cationic magnesium complex catalyzes the hydrophosphination of PhC≡CH with HPPh2, for which an FLP-type mechanism is tentatively proposed.
- Pahl, Jürgen,Stennett, Tom E.,Volland, Michel,Guldi, Dirk M.,Harder, Sjoerd
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supporting information
p. 2025 - 2034
(2019/01/14)
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- Lithium-Aluminate-Catalyzed Hydrophosphination Applications
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Synthesized, isolated, and characterized by X-ray crystallography and NMR spectroscopic studies, lithium phosphidoaluminate iBu3AlPPh2Li(THF)3 has been tested as a catalyst for hydrophosphination of alkynes, alkenes, and carbodiimides. Based on the collective evidence of stoichiometric reactions, NMR monitoring studies, kinetic analysis, and DFT calculations, a mechanism involving deprotonation, alkyne insertion, and protonolysis is proposed for the [iBu3AlHLi]2 aluminate catalyzed hydrophosphination of alkynes with diphenylphosphine. This study enhances further the development of transition-metal-free, atom-economical homogeneous catalysis using common sustainable main-group metals.
- Pollard, Victoria A.,Young, Allan,McLellan, Ross,Kennedy, Alan R.,Tuttle, Tell,Mulvey, Robert E.
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supporting information
p. 12291 - 12296
(2019/08/02)
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- Markovnikov versus anti-Markovnikov Hydrophosphination: Divergent Reactivity Using an Iron(II) β-Diketiminate Pre-Catalyst
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The ability to tune between different regioselectivities using a common pre-catalyst is an unusual yet highly desirable process. Here, we report the use of an iron(II) pre-catalyst that can be used to synthesize vinyl phosphines in a Markovnikov-selective
- King, Andrew K.,Gallagher, Kimberley J.,Mahon, Mary F.,Webster, Ruth L.
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supporting information
p. 9039 - 9043
(2017/07/11)
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- Double hydrophosphination of alkynes promoted by rhodium: The key role of an N-heterocyclic carbene ligand
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The regioselective double hydrophosphination of alkynes mediated by rhodium catalysts is presented. The distinctive stereoelectronic properties of the NHC ligand prevent the catalyst deactivation by diphosphine coordination thereby allowing for the closing of a productive catalytic cycle.
- Di Giuseppe, Andrea,De Luca, Roberto,Castarlenas, Ricardo,Pérez-Torrente, Jesús J.,Crucianelli, Marcello,Oro, Luis A.
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supporting information
p. 5554 - 5557
(2016/05/09)
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- Cobalt-catalyzed syn hydrophosphination of alkynes
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Treatment of terminal and internal alkynes with diphenylphosphane in the presence of catalytic amounts of a base and cobalt (II) acetylacetonate affords, with perfect and universal syn selectivity, the (E)-alkenyldiphenylphosphane derivatives in good yiel
- Ohmiya, Hirohisa,Yorimitsu, Hideki,Oshima, Koichiro
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p. 2368 - 2370
(2007/10/03)
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- Synthesis of vinylphosphines by hydrophosphination of alkynes in the presence of transition metal complexes
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Intermolecular hydrophosphination of terminal and internal alkynes with diphenylphosphine, catalyzed by palladium and nickel complexes, was accomplished for the first time. The reaction follows the syn-addition pattern. Conditions were found which ensure
- Kazankova,Efimova,Kochetkov,Afanas'ev,Beletskaya
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p. 1465 - 1474
(2007/10/03)
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- New approach to vinylphosphines based on Pd- and Ni-catalyzed diphenylphosphine addition to alkynes
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The catalytic addition of Ph2PH to phenylacetylene regioselectively leads to the Ph2P-CH=CHPh isomer with Pd(PPh3)4 in acetonitrile and to the Ph2P-C(Ph)=CH2 isomer with Ni(acac)2/(EtO)2P(O)H in benzene. High selectivity were also obtained for the catalytic addition of Ph2PH to tBuC≡CH and to PhC≡CPh.
- Kazankova,Efimova,Kochetkov,Afanas'ev,Beletskaya,Dixneuf
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p. 497 - 500
(2007/10/03)
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- On the Reaction of 2-Pyrrolecarbaldehyde with Hetero-substituted Ethenes
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3H-Pyrrolizines 1 have been obtained from reactions of 2-pyrrolecarbaldehyde with ethenylphosphonates 2 and the phosphane oxide 5, respectively, the ratio of products depending on the structure of the educts.On varying the reaction conditions a controlled synthesis of both isomers 1e/f was achieved.Pyrrolizines, formed in a reaction of 2-pyrrolecarbaldehyde with ethenyl phenyl sulfone (3), could not be isolated since the reaction proceeded to give more complex pyrrolizine derivatives and the cyclazine 11.A mechanism is proposed for this multistep reaction.N-Alkylatio n of 2-pyrrolecarbaldehyde with dihaloalkanes has been carried out using phase transfer catalysis.
- Flitsch, Wilhelm,Lubisch, Wilfried
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p. 1424 - 1435
(2007/10/02)
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- ENEPHOSPHINILATION
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A general method is described for the formation of vinylphosphines from arylsulfonylhydrazones.Oxidation of the resulting vinylphosphines yields phosphine oxides.
- Mislankar, Dattatraya G.,Mugrage, Ben,Darling, S. D.
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p. 4619 - 4622
(2007/10/02)
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