- Isolable Copper(I) ?2-Cyclopropene Complexes
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Treatment of bis(pyrazolyl)borate ligand supported [(CF3)2Bp]Cu(NCMe) with 1,2,3-trisubstituted cyclopropenes produced thermally stable copper(I) ?2-cyclopropene complexes amenable to detailed solution and solid-state analysis. The [(CF3)2Bp]Cu(NCMe) also catalyzed [2 + 1]-cycloaddition chemistry of terminal and internal alkynes with ethyl diazoacetate affording cyclopropenes, including those used as ligands in this work. The tris(pyrazolyl)borate [(CF3)2Tp]Cu(NCMe) is a competent catalyst for this process as well. The treatment of [(CF3)2Tp]Cu with ethyl 2,3-diethylcycloprop-2-enecarboxylate substrate gave an O-bonded rather than a ?2-cyclopropene copper complex.
- Noonikara-Poyil, Anurag,Ridlen, Shawn G.,Dias, H.V.Rasika
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p. 17860 - 17865
(2020/11/30)
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- A novel approach for rhodium(iii)-catalyzed C-H functionalization of 2,2′-bipyridine derivatives with alkynes: A significant substituent effect
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We described a novel approach for the C-H functionalization of 2,2′-bipyridine derivatives with alkynes. DFT calculations and experimental data showed a significant substituent effect at the 6-position of 2,2′-bipyridine, which weakened the adjacent N-Rh bond and provided the possibility of subsequent rollover cyclometalation, C-H activation, and functionalization.
- Wu, Shaonan,Wang, Zhuo,Bao, Yinwei,Chen, Chen,Liu, Kun,Zhu, Bolin
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supporting information
p. 4408 - 4411
(2020/05/05)
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- Rhodium(iii)-catalyzed unreactive C(sp3)-H alkenylation of N-alkyl-1H-pyrazoles with alkynes
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The first example of pyrazole-directed rhodium(iii)-catalyzed unreactive C(sp3)-H alkenylation with alkynes has been described, which showed a relatively broad substrate scope with good functional group compatibility. Moreover, we demonstrated that the transitive coordinating center pyrazole could be easily removed under mild conditions.
- Li, Tongyu,Liu, Chang,Wu, Shaonan,Chen, Chen C.,Zhu, Bolin
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supporting information
p. 7679 - 7683
(2019/08/30)
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- A Mild Rhodium Catalyzed Direct Synthesis of Quinolones from Pyridones: Application in the Detection of Nitroaromatics
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A rhodium catalyzed direct regioselective oxidative annulation by double C-H activation is described to synthesize highly substituted quinolones from pyridones. The reaction proceeds at mild conditions with broad scope and wide functional group tolerance. These novel quinolones were explored to recognize nitroaromatic compounds.
- Biswas, Aniruddha,Giri, Dipanjan,Das, Debapratim,De, Anurima,Patra, Sanjib K.,Samanta, Rajarshi
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p. 10989 - 10996
(2017/10/27)
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- Lewis acid activation of molybdenum nitrides for alkyne metathesis
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The substantial kinetic barrier to molybdenum nitride-alkyne metathesis is facilitated by precomplexation of the borane Lewis acid B(C6F 5)3, providing convenient access to metathesis-active molybdenum alkylidynes. Spectroscopic and X-ray structural analysis suggest MoN bond weakening upon borane complexation.
- Finke, Aaron D.,Moore, Jeffrey S.
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supporting information; experimental part
p. 7939 - 7941
(2011/01/04)
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- Development of a well-defined silica-supported tungstenocarbyne complex as efficient heterogeneous catalyst for alkyne metathesis
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The interaction of [W({triple bond, long}C-tBu)(CH2-tBu)(OAr)2] (Ar = 2,6-iPr2C6H3) (1), with the hydroxyl groups of a silica dehydroxylated at 700 °C leads to [({triple bond, long}SiO)W(OAr)2({triple bond, long}C-tBu)] (2) which was characterized by IR, solid-state NMR and mass balance analysis. This well-defined surface species is an efficient catalyst for the metathesis of pent-2-yne.
- Merle, Nicolas,Taoufik, Mostafa,Nayer, Morad,Baudouin, Anne,Roux, Erwan Le,Gauvin, Régis M.,Lefebvre, Frédéric,Thivolle-Cazat, Jean,Basset, Jean-Marie
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p. 1733 - 1737
(2008/09/18)
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- Highly active molybdenum-alkylidyne catalysts for alkyne metathesis: Synthesis from the nitrides by metathesis with alkynes
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Terminal nitrido complexes N≡Mo(OC(CF3)2Me)3 (4), N≡Mo(OC(CF3)2Me)3(NCMe) (4-NCMe), and NMo(OC(CF3)3)3(NCMe) (5-NCMe) react irreversibly with 3-hexyne at elevated temperature in hydrocarbon solution to form the corresponding propylidyne complexes EtC≡Mo(OC(CF3)2Me)3 (3) and EtC≡Mo(OC(CF3)3)3 (6), long known as exceptionally active catalysts for alkyne metathesis. The propylidyne complexes are isolated as the more readily crystallized 1,2-dimethoxyethane (DME) adducts for convenience; 3-DME is isolated in 61% yield on a multigram scale. Copyright
- Gdula, Robyn L.,Johnson, Marc J. A.
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p. 9614 - 9615
(2007/10/03)
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- A highly active, heterogeneous catalyst for alkyne metathesis
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(Chemical Equation Presented) An alkylidyne molybdenum amide complex is attached to nontoxic, amorphous silica to form a highly active, recyclable heterogeneous catalyst for alkyne metathesis. The catalyst does not undergo alkyne polymerization, can be utilized at a loading of 1 mol% at room temperature, and has shown unprecedented metathesis activity for the homodimerization of 2-propynylthiophene, a substrate that was previously problematic for alkyne metathesis.
- Weissman, Haim,Plunkett, Kyle N.,Moore, Jeffrey S.
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p. 585 - 588
(2007/10/03)
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- HETEROGENEOUS ALKYNE METATHESIS
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The present invention provides heterogeneous organometallic catalysts for alkyne metathesis, including the metathesis of internal alkynes. Organometallic precursors are covalently bonded to the oxygen atoms of metal oxide supports to form catalysts having carbyne functionality. The heterogeneous catalysts provide improved turn-over frequencies at lower reaction temperatures than conventional catalysts.
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Page/Page column 7; 8
(2008/06/13)
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- Iridium complex-catalyzed [2+2+2] cycloaddition of α,ω-diynes with monoynes and monoenes
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[Ir(cod)Cl]2/DPPE was found to be a new catalyst for the cycloaddition of α,ω-diynes with monoynes to give polysubstituted benzene derivatives in high yields. Internal monoynes as well as terminal monoynes could be used. The reaction tolerates a broad range of functional groups such as alcohol, amine, alkene, ether, halogen, and nitrile. The reaction of 1,6-octadiyne derivatives with 1-alkynes gives ortho products and meta products. The regioselectivity could be controlled by the choice of ligand. The reaction with DPPE was meta selective, with meta selectivity of up to 82%. The reaction with DPPF was ortho selective, with ortho selectivity of up to 88%. We propose a mechanism to account for this regioseleetive cycloaddition. [Ir(cod)Cl]2/DPPE also catalyzed the cycloaddition of α,ω-diynes with 2,5-dihydrofuran to give bicyclic cyclohexadiene derivatives. The reaction with 2,3-dihydrofuran and n-butyl vinyl ether gave benzene derivatives instead of cyclohexadiene derivatives. We also propose a mechanism to account for this novel aromatization that includes cleavage of the C-O bond.
- Kezuka, Satoko,Tanaka, Shigeru,Ohe, Toshihito,Nakaya, Yoshihiko,Takeuchi, Ryo
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p. 543 - 552
(2007/10/03)
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- Sodium methylthiolate as an efficient deprotecting agent for dicobalt hexacarbonyl complexes of acetylenes
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Various dicobalt hexacarbonyl acetylene complexes were efficiently converted to the unprotected acetylene by the reaction of two molar equivalents of sodium methylthiolate. Yields and reaction times depend upon the choice of solvent. DMF proved to be the
- Davis, D. Scott,Shadinger, Sylvia C.
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p. 7749 - 7752
(2007/10/03)
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- Formation, fragmentation, and isomerization of titanacycle rings supported by aryloxide ligation
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The reactivity of the titanacyclopentadiene ring in [(Ar″O)2Ti(C4Et4)] can best be explained on the basis of facile fragmentation into a titanium bis(alkyne) complex.
- Hill, John E.,Fanwick, Phillip E.,Rothwell, Ian P.
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p. 2211 - 2213
(2008/10/08)
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- Homogeneous Metathesis of Functionalized Alkynes
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Various functionalized disubstituted acetylenes, including esters, are prepared metathetically with high selectivity on molybdenum based homogeneous catalytic systems; this procedure is a useful tool for the synthesis of acetylenes, which can provide cis- or trans-olefins by further selective hydrogenation.
- Petit, Michele,Mortreux, Andre,Petit, Francis
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p. 1385 - 1386
(2007/10/02)
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- Stereochemistry of Olefin and Fatty Acid Oxidation. Part 1. Autooxidation of Hexene and Hepta-2,5-diene Isomers
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The stereochemistry of the autooxidation of hex-1-ene, cis- and trans-hex-2-ene, cis- and trans-hex-3-ene, and of the three geometrical isomers of hepta-2,5-diene, has been determined by the reduction of the hydroperoxides produced and analysis of the resulting allylic alcohols.The relative proportions of the isomeric hydroperoxides are explicable in termes of the conformation of the parent olefins which are capable of giving delocalised radicals on hydrogen abstraction.
- Frankel, Edwin N.,Garwood, Robert F.,Vinson, John R.,Weedon, Basil C. L.
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p. 2707 - 2714
(2007/10/02)
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- KETENE-ANTHRACENE ADDUCT, A PRECURSOR OF SUBSTITUTED ACETYLENES
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The ketene-anhracene adduct 1 serves as a good precursor in the synthesis of substituted acetylenes, in wich the key step is the retro Diels-Alder reaction.
- Tarnchompoo, Bongkoch,Thebtaranonth, Yodhathai,Utamapanya, Suchada,Kasemsri, Prapani
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p. 1241 - 1242
(2007/10/02)
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