- Interaction of the buchwald seven-membered zirconacyclocumulene complex with carbonyl compounds
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The interaction of the Buchwald seven-membered zirconacyclocumulene Cp2Zr[4-Me3SiC4(SiMe3)-C(C2SiMe3)=CSiMe3] (1) with a 2-fold excess of benzophenone in toluene at 100 °C for 20 h results in the formation of Me3SiCC-CCSiMe3 and a nine-membered dioxazirconacycle Cp2Zr[2-OC(Ph)2C(SiMe3)C2C(SiMe3)C(Ph)2O] (5) containing [3]cumulene group in the ring. Analogous metallacycle (6) is formed on heating of 1 with fluorenone in toluene at 100 °C. A treatment of 5 with HCl in dioxane at 20 °C affords Cp2ZrCl2 and cis-[3]cumulenic diol Ph2(HO)C(Me3Si)CC2C(SiMe3)C(OH)Ph2 (7) in 85% yield. The reaction of 1 with benzil (PhCO)2 at 80 °C in benzene proceeds differently than with benzophenone and fluorenone. In this case, a nine-membered dioxazirconacycle Cp2Zr[2-Me3SiCaC(C2SiMe3)-C(SiMe3) C(C2SiMe3)OC(Ph) C(Ph)O] (10) is produced. The nature of products formed in the interaction of 1 with acenaphthenequinone proved to be temperature dependent. Thus, on carrying out the reaction at 20 °C, an 11-membered trioxazirconacycle (11) containing three CaC bonds in the ring was isolated from the mixture, whereas at 80 °C the reaction gave a ten-membered tetraoxadizirconacycle (12) and octasubstituted cyclooctatetraene [(Me3Si)CaC(CCSiMe3)]4 (13). The structures of 5-7 and 10-13 have been determined by X-ray diffraction. The mechanism of the reactions found is discussed.
- Burlakov, Vladimir V.,Andreev, Maxim V.,Bogdanov, Vyacheslav S.,Smol'Yakov, Alexander F.,Minacheva, Mariya Kh.,Shur, Vladimir B.
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Read Online
- Cooperative assembly of a double-stranded hydrogen-bonded porphyrin zip
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A linear zinc porphyrin dimer has been used for the first time to stabilise two identical non-covalent aggregates by a combination of N-pyridyl zinc binding and hydrogen bonding. An improved multigram synthesis of 5,15-bis-(3,5-di-tert-butylphenyl)-10,20-
- Plater, M. John,Aiken, Stuart,Bourhill, Grant
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Read Online
- Tuning of cross-Glaser products mediated by substrate-catalyst polymeric backbone interactions
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Tuning of cross-Glaser products using different polymeric backbones supported by copper oxide nano-catalysts has been demonstrated by tweaking the substrate-catalyst interactions under greener conditions. Further, highly reactive magnetically separable and recyclable catalyst with scalability is demonstrated.
- Ali, Md. Ehesan,Dar, Arif Hassan,Gowri, Vijayendran,Jayamurugan, Govindasamy,Kaur, Sharanjeet,Mukhopadhyaya, Aritra,Neethu, K. M.,Sartaliya, Shaifali,Selim, Abdul
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supporting information
p. 2582 - 2585
(2020/03/10)
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- Copper Catalysis for Selective Heterocoupling of Terminal Alkynes
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A Cu-catalyzed selective aerobic heterocoupling of terminal alkynes is disclosed, which enables the synthesis of a broad range of unsymmetrical 1,3-diynes in good to excellent yields. The results disprove the long-held belief that homocouplings are exclusively favored in the Glaser-Hay reaction.
- Su, Lebin,Dong, Jianyu,Liu, Long,Sun, Mengli,Qiu, Renhua,Zhou, Yongbo,Yin, Shuang-Feng
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supporting information
p. 12348 - 12351
(2016/10/07)
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- Halogen bonding of (iodoethynyl)benzene derivatives in solution
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Halogen bonding (XB) between (iodoethynyl)benzene donors and quinuclidine in benzene affords binding free enthalpies (δG, 298 K) between -1.1 and -2.4 kcal mol-1, with a strong LFER with the Hammett parameter σpara. The enthalpic dri
- Dumele, Oliver,Wu, Dino,Trapp, Nils,Goroff, Nancy,Diederich, Francois
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supporting information
p. 4722 - 4725
(2015/04/27)
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- Cyclization of gold acetylides: Synthesis of vinyl sulfonates via gold vinylidene complexes
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Differently substituted terminal alkynes that bear sulfonate leaving groups at an appropriate distance were converted in the presence of a propynyl gold(I) precatalyst. After initial formation of a gold acetylide, a cyclization takes place at the β-carbon atom of this species. Mechanistic studies support a mechanism that is related to that of dual gold-catalyzed reactions, but for the new substrates, only one gold atom is needed for substrate activation. After formation of a gold vinylidene complex, which forms a tight contact ion pair with the sulfonate leaving group, recombination of the two parts delivers vinyl sulfonates, which are valuable targets that can serve as precursors for cross-coupling reactions, for example. Gold vinylidene intermediates are generated by the cyclization of gold acetylides that carry a sulfonate leaving group. This result demonstrates for the first time that the formation of these species is not restricted to a dual activation mode. The cyclization products obtained herein contain a vinyl sulfonate moiety, which makes them useful building blocks for cross-coupling reactions.
- Bucher, Janina,Wurm, Thomas,Nalivela, Kumara Swamy,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 3854 - 3858
(2014/05/06)
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- Metal-free 1,5-regioselective azide-alkyne [3+2]-cycloaddition
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[3+2]-cycloaddition reactions of aromatic azides and silylated alkynes in aqueous media yield 1,5-disubstituted-4-(trimethyl-silyl)-1H-1,2,3-triazoles. The formation of the 1,5-isomer is highly favored in this metal-free cycloaddition, which could be proven by 1D selective NOESY and X-ray investigations. Additionally, DFT calculations corroborate the outstanding favoritism regarding the 1,5-isomer. The described method provides a simple alternative protocol to metal-catalyzed "click chemistry" procedures, widening the scope for regioselective heavy-metal-free synthetic applications.
- Kloss, Florian,Koehn, Uwe,Jahn, Burkhard O.,Hager, Martin D.,Goerls, Helmar,Schubert, Ulrich S.
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supporting information; experimental part
p. 2816 - 2824
(2012/06/01)
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- Fluoro-substituted phenyleneethynylenes: Acetylenic n-type organic semiconductors
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Fluoro-substituted phenyleneethynylenes are synthesized by Sonogashira coupling and acetylide-nucleophilic substitution of fluorobenzenes. Fluoro-substitution of benzenes enables deep LUMO potential, and CF 3-substitution provides high electron
- Matsuo, Daisuke,Yang, Xin,Hamada, Akiko,Morimoto, Kyo,Kato, Takuji,Yahiro, Masayuki,Adachi, Chihaya,Orita, Akihiro,Otera, Junzo
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supporting information; experimental part
p. 1300 - 1302
(2011/02/17)
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- The sequential Sonogashira-click reaction: A versatile route to 4-aryl-1,2,3-triazoles
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Aryl halides can be easily transformed in a one-pot procedure into 4-aryl-1,2,3-triazoles with palladium/copper-catalyzed Sonogashira-click reaction sequence, using trimethylsilylacetylene as acetylene surrogate.
- Loerincz, Krisztian,Kele, Peter,Novak, Zoltan
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body text
p. 3527 - 3532
(2010/02/28)
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- 4-Amino-5-aryl-6-arylethynylpyrimidines: Structure-activity relationships of non-nucleoside adenosine kinase inhibitors
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A series of non-nucleoside adenosine kinase (AK) inhibitors is reported. These inhibitors originated from the modification of 5-(3-bromophenyl)-7-(6-morpholin-4-ylpyridin-3-yl)pyrido[2,3-d]pyrimidin-4-ylamine (ABT-702). The identification of a linker that would approximate the spatial arrangement found between the pyrimidine ring and the aryl group at C(7) in ABT-702 was a key element in this modification. A search of potential linkers led to the discovery of an acetylene moiety as a suitable scaffold. It was hypothesized that the aryl acetylenes, ABT-702, and adenosine bound to the active site of AK (closed form) in a similar manner with respect to the orientation of the heterocyclic base. Although potent acetylene analogs were discovered based on this assumption, an X-ray crystal structure of 5-(4-dimethylaminophenyl)-6-(6-morpholin-4-ylpyridin-3-ylethynyl)pyrimidin-4-ylamine (16a) revealed a binding orientation contrary to adenosine. In addition, this compound bound tightly to a unique open conformation of AK. The structure-activity relationships and unique ligand orientation and protein conformation are discussed.
- Matulenko, Mark A.,Paight, Ernest S.,Frey, Robin R.,Gomtsyan, Arthur,DiDomenico Jr., Stanley,Jiang, Meiqun,Lee, Chih-Hung,Stewart, Andrew O.,Yu, Haixia,Kohlhaas, Kathy L.,Alexander, Karen M.,McGaraughty, Steve,Mikusa, Joseph,Marsh, Kennan C.,Muchmore, Steven W.,Jakob, Clarissa L.,Kowaluk, Elizabeth A.,Jarvis, Michael F.,Bhagwat, Shripad S.
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p. 1586 - 1605
(2008/02/01)
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- Synthesis of alkylene-bridged diphenyl-oligoynes
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A general synthesis route for the preparation of oligoynes stabilized by alkylene bridges is reported. The corresponding macrocycles contain oligoynes with up to eight conjugated triple bonds. The stabilization of the conjugated sp-oligoyne rods was achieved by bulky terminal phenylic endcaps spanning the alkylene chain to isolate the individual acetylenic rods and to avoid polymerization. Alkylene chains with up to 40 methylene groups were employed. The two terminal acetylene functions were introduced prior to the oligoyne elongation by twofold introduction of additional C2-acetylene or C4-butadiyne building blocks. The final step was the intramolecular acetylene coupling upon which very large macrocycles with up to 62 ring members containing segregated sp-, sp2- and sp3-segments were formed. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Klinger, Christian,Vostrowsky, Otto,Hirsch, Andreas
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p. 1508 - 1524
(2007/10/03)
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- The behaviors of metal acetylides with dinitrogen tetroxide
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Lithium phenylacetylide (1a) and N2O4 (2) at - 78° yield diphenylbutadiyne (6a) by oxidative coupling, phenylacetylene (7a) by oxidation and then solvent H-abstraction, and benzoyl cyanide (8) by dimerizative-rearrangement of nitroso(phenyl)acetylene (23). Nitro(phenyl)acetylene (3, R = Ph) is not obtained. Benzonitrile (9), a further product, possibly results from hydrolytic decomposition of nitroso(phenyl)ketene (27) generated from phenylacetylenyl nitrite (26). Phenylacetylene (7a) and 2 give, along with (E)- and (Z)-1,2-dinitrostyrenes (34 and 35, resp.), 3-benzoyl-5-phenylisoxazole (10), presumably as formed by cycloaddition of benzoyl nitrile oxide (40) to 7a. Further, 2 reacts with other lithium acetylides (1b-1e), and with sodium, magnesium, zinc, copper, and copper lithium phenylacetylides, 1f-1l, to yield diacetylenes 6a-6c and monoacetylenes 7a-7c. Conversions of metallo acetylide aggregates to diacetylenes are proposed to involve generation and addition reactions of metallo acetylide radical cationic intermediates in cage, further oxidation, and total loss of metal ion. Loss of metal ions from metallo acetylide radical cations and H-abstraction by non-caged acetylenyl radicals will give terminal acetylenes. The principal reactions (75-100%) of heavy metal acetylides phenyl(trimethylstannyl)acetylene (44) and bis(phenylacetylenyl)mercury (47) with 2 are directed nitrosative additions (NO+) and loss of metal ions to give nitroso(phenyl)ketene (27), which converts to benzoyl cyanide (8).
- Woltermann, Christopher J.,Shechter, Harold
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p. 354 - 369
(2007/10/03)
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- Synthesis, light harvesting, and energy transfer properties of a Zinc porphyrin linked poly(phenyleneethynylene)
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The synthesis of a zinc porphyrin linked conjugated homopolymer is presented. The synthetic strategy employed a directional polymerization of 1-iodo-2,5-dioctyl-4'-ethynyltolane in the presence of [10,20-bis(3,5-bis-tert- butylphenyl]-5,15-diethynylporphinato]zinc(II) (12) or [10,20-bis(3,5-bis-tert- butylphenyl]-5,15-dibromoporphinato]zinc(II) (10). In the case of 12 the reaction was found to give a polymer product with a constant ratio of zinc porphyrin to incorporated monomer units regardless of the molecular weight. In the case of 10, however, the ratio of zinc porphyrin to incorporated monomer units decreased with increasing molecular weight of the polymer product. The polymer products were separated into fractions using preparative SEC. Studies of the energy transfer properties from the polymer to the zinc porphyrin revealed that there was little energy transfer in solution but quantitative energy transfer in the solid state. The polymer products proved difficult to handle in terms of device construction where a thin polymer film is sandwiched between two electrodes. We found this to be a consequence of the palladium catalysis employed during the polymerization. We finally discuss the issues concerning the problems with remnants from the Pd catalyst in the polymer samples and their removal.
- Nielsen, Kim T.,Spanggaard, Holger,Krebs, Frederik C.
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p. 1180 - 1189
(2007/10/03)
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- Preparation of fullerene-polyyne nanospheres via thermally induced solid-state polymerization
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A 1,3,5,7-octatetrayne-linked bis(fullerene) compound has been synthesized. Through a thermally induced solid-state polymerization reaction on a surface, the solid thin film of this compound was transformed into a highly uniform and well organized polymer
- Zhou, Ningzhang,Merschrod, Erika F. S.,Zhao, Yuming
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p. 14154 - 14155
(2007/10/03)
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- Aryl alkynylation versus alkyne homocoupling: Unprecedented selectivity switch in Cu, phosphine and solvent-free heterogeneous Pd-catalysed couplings
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Sonogashira reaction and oxidative dimerisation of terminal alkynes are among the most relevant and attractive C-C bond forming transformations in the metallo-catalysed cross-coupling scenario. Often, the homocoupling reactions of substituted acetylenic derivatives are concomitant to the Sonogashira pathway and time-consuming optimization procedures are required in order to reach satisfactory levels of selectivity. In this paper, the potential of a class of Pd-complexes loaded to mesoporous silica gel in promoting the Sonogashira reaction between aryl acetylenes and iodoarenes is underlined. This family of heterogeneous organo-palladium systems allows the desired cross-coupled compounds to be isolated in excellent yield under very mild conditions. In fact, the absence of organic solvents, copper(I) co-catalyst and phosphane ligands, (which are easily oxidisable and whose preparation has a heavy environmental impact), in conjunction with the low catalyst loading ([Pd] 0.1-1 mol%) and its recoverability, stresses the environmental benefits of the protocol. The Sonogashira/homocoupling selectivity proved to be function of the haloarene employed. As a matter of fact, while iodoarenes bearing EWG (electron withdrawing groups) on the phenyl ring underwent smoothly the Sonogashira pathway, electron-rich iodobenzenes showed opposite behaviour by mainly furnishing the homocoupling product. The use of bromoarenes provided solely the homocoupling product in excellent yield without themselves being consumed. This is despite that fact that the catalysts used activate bromoarenes equally as well as iodoarenes in both Heck and Suzuki systems. Kinetic investigations revealed a highly temperature-dependent profile, which indicates strongly that the reaction takes place at the surface. Finally, the full heterogeneous character of the catalytically active species as well as the reusability of the immobilised Pd-complex were confirmed by hot-filtration test and by multiple reuses of the supported catalyst in subsequent Sonogashira cross-couplings.
- Bandini, Marco,Luque, Rafael,Budarin, Vitaly,Macquarrie, Duncan J.
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p. 9860 - 9868
(2007/10/03)
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- Synthese von [(η5-C5H5)2Ti(Cl)(CCSiMe3)]Ni(CO) und dessen Reaktionverhalten gegenueber Phosphiten: die Festkoerperstruktur von (CO)2Ni[P(OC6H4CH3-2)3]2
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Treatment of [Ti](Cl)(CCSiMe3) (1) {[Ti]=(η5-C5H5)2Ti} with Ni(CO)4 (2) in a 1:1 molar ratio produces the heterobimetallic early-late transition metal complex {[Ti](Cl)(CCSiMe3)}Ni(CO) (3), which features a low-valent Ni(CO) entity stabilized by a datively bonded Cl and a η2-coordinated Me3SiCC ligand. As side-products [Ti]Cl2 (8) and {[Ti](CCSiMe3)2}Ni(CO) (5) are formed. The latter complex can also be synthesized by the reaction of [Ti](CCSiMe3)2 (4) with equimolar amounts of 2. If 3 is reacted with stoichiometric amounts of P(OR)3 (6a, R=C6H5; 6b, R=C6H4CH3-2; 6c, R=C6H4t-Bu-2) the bis(alkynyl) titanocene 4, (CO)2Ni[P(OR)3]2 (7a, R=C6H5; 7b, R=C6H4CH3-2; 7c, R=C6H4t-Bu-2), complex 8, {[Ti](μ,η1:η2-CCSiMe3)}2 (9) along with Me3SiCC-CCSiMe3 (10) is produced. A possible mechanism for the formation of these species is presented. The solid-state structure of 7b is reported. Complex 7b crystallizes in the tetragonalic space group P-421c with the following parameters: a=14.852(2), b=14.852(2), c=19.410(4) Angstroem, V=4281.5(12) Angstroem3, Z=4 and ρ=1.271 g cm-3. Mononuclear 7b features a Ni(O) centre in a pseudo-tetrahedral environment, caused by the CO and P(OC6H4CH3-2)3 ligands.
- Meichel, E.,Stein, Th.,Kralik, J.,Rheinwald, G.,Lang, H.
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p. 191 - 198
(2007/10/03)
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- Pyrolyse von Uebergangsmetallkomplexen: Darstellung von Metallcarbiden (MC, M2C) aus metallorganischen Verbindungen
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The following compounds were prepared and their pyrolysis in a stream of argon was studied: 5-C5H5)(CO)2>2 (1), 5-C5H5)(CO)3>2 (2, M=Mo; 3, M=W), 5-C5H5)(CO)2(CCSiMe3)> (4), 5-C5H5)(CO)3(CCSiMe3)> (5 M = Mo; 6, M=W), 5-C5H5)3(CO)7(μ-η2:2:1-CCSiMe3)> (7), 5-C5H5)2(CO)4(μ-η2:2-HCCC6H5)> (8), 5-C5H5)2(CO)4(μ-η2:2-RCC-SiR'R''-CCR> (9a, R=H, R'=R''=CH3; 9b, R=C6H5, R'=H, R''=CH3; 9c, R=C6H5, R'=CH=CH2, R''=CCC6H5), 5-C5H5)2(CO)4(μ-η2:2-Me3SiCC-CCSiMe3)> (10), 5-C5H5)4(CO)8(μ4-η2:2:2:2-Me3SiCC-CCSiMe3)> (11).The products of bulk pyrolysis of selected compounds are formed in 20percent-60percent yield, based on the charged sample weight.The ceramic materials obtained consist of metal carbides (MC, M2C) together with small amounts of metal(0) (M=Mo, W) and amorphous carbon.Keywords: Pyrolysis; Preceramics; Ceramics; Iron; Molybdenum; Tungsten
- Lang, Heinrich,Blau, Sabine,Rheinwald, Gerd,Wildermuth, Gerhard
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p. C17 - C21
(2007/10/02)
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- Synthesis of High Carbon Materials from Acetylenic Precursors. Preparation of Aromatic Monomers Bearing Multiple Ethynyl Groups
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The synthesis of polyethynyl aromatics as starting materials for the preparation of highly cross-linked organic solids containing high atom fractions of carbon is described.Treatment of bromo- and iodoaromatic compounds with (trimethylsilyl)acetylene (TMSA) in the presence of palladium(O) and copper(I) in amine solvents yields (trimethylsilyl)ethynyl-substituted aromatics.The TMS protecting groups can be removed by hydrolysis with mild base.Compounds prepared by using this technique include 1,3-diethynylbenzene, 2,5-diethynylthiophene, 1,3-diethynyltetrafluorobenzene, 1,4-diethynyltetrafluorobenzene, 2-ethynylthiazole, 2,4-diethynylthiazole, 2,7-diethynylnaphthalene, hexakis((trimethylsilyl)ethynyl)benzene, tetraethynylthiophene, 2,5-bis((trimethylsilyl)ethynyl)-3,4-bis(3-hydroxy-3-methyl-1-butynyl)thiophene, 2,5-diethynyl-3,4-bis(3-hydroxy-3-methyl-1-butynyl)thiophene, 2,5-bis(4-(2-thienyl)butadiynyl)-3,4-bis(3-hydroxy-3-methyl-1-butynyl)thiophene, and 2,5-bis-(4-(2-thienyl)butadiynyl)-3,4-diethynylthiophene.
- Neenan, Thomas X.,Whitesides, George M.
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p. 2489 - 2496
(2007/10/02)
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- Action du chlorure de fer(III) sur des acetyleniques substitues par des elements de la colonne IVB. Formation de diynes
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We have studied the behaviour of mono- and diheterosubstituted acetylenies (1,2,3) in the presence of iron(III) chloride in a carbon tetrachloride-toluene medium at 25 deg C. 1: ; 2: ; 3: .The reaction always takes place in heterogeneous phase, the reaction medium being carefully kept free from air and humidity. Compounds of type 1. The reaction rate increases from the carbon compound to the stannyl compound. The germyl and stannyl acetylenics give 2,4-hexadiyne with good yields, respectively 62 and 84percent . Compounds of types 2 and 3. The influence of heterosubstituents on the reaction rate is the same as for compounds 1.For the mixed compound 3b, only one hexadiyne can be obtained with a yield of 90percent, gis(trimethylsilyl)buta-1,3-diyne.In the course of all these reactions, iron(III) is reduced into iron(II). The influence of the metal and its substituents as well as the action of iron chloride on the various conjugated diynes are discussed.A mechanism based on the respective reaction rates is suggested.
- Braun, Jacques,Trung, Bui Khac
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