- Scandium complexes with the tetraphenylethylene and anthracene dianions
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The structural study of Sc complexes containing dianions of anthracene and tetraphenylethylene should shed some light on the nature of rare-earth metal-carbon bonding. The crystal structures of (18-crown-6)bis(tetrahydrofuran-κO)sodium bis(η6-1,1,2,2-tetraphenylethenediyl)scandium(III) tetrahydrofuran disolvate, [Na(C4H8O)2(C12H24O6)][Sc(C26H20)2]·2C4H8O or [Na(18-crown-6)(THF)2][Sc(η6-C2Ph4)2]·2(THF), (1b), (η5-1,3-diphenylcyclopentadienyl)(tetrahydrofuran-κO)(η6-1,1,2,2-tetraphenylethenediyl)scandium(III) toluene hemisolvate, [Sc(C17H13)(C26H20)(C4H8O)]·0.5C7H8 or [(η5-1,3-Ph2C5H3)Sc(η6-C2Ph4)(THF)]·0.5(toluene), (5b), poly[[(μ2-η3:η3-anthracenediyl)bis(η6-anthracenediyl)bis(η5-1,3-diphenylcyclopentadienyl)tetrakis(tetrahydrofuran)dipotassiumdiscandium(III)] tetrahydrofuran monosolvate], {[K2Sc2(C14H10)3(C17H13)2(C4H8O)4]·C4H8O}n or [K(THF)2]2[(1,3-Ph2C5H3)2Sc2(C14H10)3]·THF, (6), and 1,4-diphenylcyclopenta-1,3-diene, C17H14, (3a), have been established. The [Sc(η6-C2Ph4)2]-complex anion in (1b) contains the tetraphenylethylene dianion in a symmetrical bis-η3-allyl coordination mode. The complex homoleptic [Sc(η6-C2Ph4)2]-anion retains its structure in THF solution, displaying hindered rotation of the coordinated phenyl rings. The1D1H and13C{1H}, and 2D COSY1H-1H and13C-1H NMR data are presented for M[Sc(Ph4C2)2]·xTHF [M = Na and x = 4 for (1a); M = K and x = 3.5 for (2a)] in THF-d8 media. Complex (5b) exhibits an unsymmetrical bis-η3-allyl coordination mode of the dianion, but this changes to a η4 coordination mode for (1,3-Ph2C5H3)Sc(Ph4C2)(THF)2, (5a), in THF-d8 solution. A 45Sc NMR study of (2a) and UV-Vis studies of (1a), (2a) and (5a) indicate a significant covalent contribution to the Sc-Ph4C2 bond character. The unique Sc ate complex, (6), contains three anthracenide dianions demonstrating both a η6-coordination mode for two bent ligands and a μ2-η3:η3-bridging mode of a flat ligand. Each [(1,3-Ph2C5H3)2Sc2(C14H10)3]2-dianionic unit is connected to four neighbouring units via short contacts with [K(THF)2]+ cations, forming a two-dimensional coordination polymer framework parallel to (001).
- Ellis, John E.,Minyaev, Mikhail E.,Nifant’Ev, Ilya E.,Churakov, Andrei V.
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- Synthesis of a Tetraphenyl-Substituted Dihydropentalene and Its Alkali Metal Hydropentalenide and Pentalenide Complexes
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We report a high-yielding solution phase synthesis of 1,3,4,6-tetraphenyl-dihydropentalene based on a simple annulation reaction of cyclopentadiene with a chalcone. Deprotonative metalation of 1,3,4,6-tetraphenyl-dihydropentalene with alkali metal bases (
- Boyt, Stuart M.,Jenek, Niko A.,Sanderson, Hugh J.,Kociok-K?hn, Gabriele,Hintermair, Ulrich
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p. 211 - 225
(2021/11/17)
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- Gold-Catalyzed Rearrangement of Alkynyl Donor-Acceptor Cyclopropanes to Construct Highly Functionalized Alkylidenecyclopentenes
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A gold-catalyzed 1,7-addition-cyclization-elimination cascade sequence performed on a range of alkynyl-substituted donor-acceptor-type cyclopropanes provides facile entry to highly functionalized exo-alkylidenecyclopentenes under very mild conditions. Iso
- Chen, Huiyu,Zhang, Jing,Wang, David Zhigang
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p. 2098 - 2101
(2015/05/13)
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- A radical-anion chain mechanism following dissociative electron transfer reduction of the model prostaglandin endoperoxide, 1,4-diphenyl-2,3- dioxabicyclo[2.2.1]heptane
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The model prostaglandin endoperoxide, 1,4-diphenyl-2,3-dioxabicyclo[2.2.1] heptane (3), was investigated in N,N-dimethylformamide at a glassy carbon electrode using various electrochemical techniques. Reduction of 3 occurs by a concerted dissociative electron transfer (ET) mechanism. Electrolysis at -1.6 V yields 1,3-diphenyl-cyclopentane-cis-1,3-diol in 97% by a two-electron mechanism; however, in competition with the second ET from the electrode, the resulting distonic radical-anion intermediate undergoes a β-scission fragmentation. The rate constant for the heterogeneous ET to the distonic radical-anion is estimated to occur on the order of 2 × 107 s-1. In contrast, electrolyses conducted at potentials more negative than -2.1 V yield a mixture of primary and secondary electrolysis products including 1,3-diphenyl-cyclopentane-cis-1,3-diol, 1,3-diphenyl-1,3-propanedione, trans-chalcone and 1,3-diphenyl-1,3-hydroxypropane by a mechanism involving less than one electron equivalent. These observations are rationalized by a catalytic radical-anion chain mechanism, which is dependent on the electrode potential and the concentration of weak non-nucleophilic acid. A thermochemical cycle for calculating the driving force for β-scission fragmentation from oxygen-centred biradicals and analogous distonic radical-anions is presented and the results of the calculations provide insight into the reactivity of prostaglandin endoperoxides.
- Magri, David C.,Workentin, Mark S.
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p. 3354 - 3361
(2009/02/05)
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- Ruthenium-catalyzed cycloisomerization of cis-3-en-1-ynes to cyclopentadiene and related derivatives through a 1,5-sigmatropic hydrogen shift of ruthenium vinylidene intermediates
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We report a new ruthenium-catalyzed cycloisomerization of unactivated cis-3-en-1-ynes, which produces substituted cyclopentadiene and related derivatives. The mechanism of this cyclization is proposed to involve a [1,5]-sigmatropic hydrogen shift of ruthenium-vinylidene intermediates on the basis of deuterium-labeling experiments. Copyright
- Datta, Swarup,Odedra, Arjan,Liu, Rai-Shung
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p. 11606 - 11607
(2007/10/03)
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- Deoxygenation of 1,3-Diene 1,4-Endoperoxides by Tin(II) Chloride
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The reaction of bicyclic 1,3-diene 1,4-endoperoxides with SnCl2 re-generated the corresponding dienes in 15-70percent yield.The efficiency of the deoxygenation depended on the structure of peroxides.The results were compared with those of Fe(II) as well as Pd(0) assisted reactions.
- Kohmoto, Shigeo,Kasai, Satoru,Yamamoto, Makoto,Yamada, Kazutoshi
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p. 1477 - 1478
(2007/10/02)
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- CYCLIC TRIMERIZATION OF ACETYLENES TO FULVENES
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The catalytic transformation of acetylene and its derivatives at palladium complexes was investigated.Acetylene, phenylacetylene, and tert-butylacetylene are converted into the fulvene valence isomers of benzene in the presence of cationic bisarene complexes of palladium Pd(AlCl4)2*2C6H6 and Pd(Al3Cl7)2*2C6H6 and also in the presence of Pd(OAc)2 and Pd.
- Chukhadzhyan, G. A.,Abramyan, Zh. I.,Tonyan, G. M.,Sagradyan, L. I.,Elbakyan, T. S.
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p. 1636 - 1640
(2007/10/02)
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- Response of acidity and magnetic resonance properties to aryl substitution in carbon acids and derived carbanions: 1-Aryl-4-phenylcyclopenta-1,3-dienes. Dependence of ionic structure on aryl substitution
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Monosubstitution on one aryl ring of 1,4-diphenylcyclopenta-1,3-diene provides a probe for studying anion stability, charge density, and ionic structure. We have measured the pKa's of several members of this series in both pure Me2SO
- Greifenstein, Linda G.,Lambert, Joseph B.,Nienhuis, Ronald J.,Drucker, George E.,Pagani, Giorgio A.
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p. 7753 - 7761
(2007/10/06)
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