- Single-Molecule Conductance Studies of Organometallic Complexes Bearing 3-Thienyl Contacting Groups
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The compounds and complexes 1,4-C6H4(C≡C-cyclo-3-C4H3S)2(2), trans-[Pt(C≡C-cyclo-3-C4H3S)2(PEt3)2] (3), trans-[Ru(C≡C-cyclo-3-C4H3S)2(dppe)2] (4; dppe=1,2-bis(diphenylphosphino)ethane) and trans-[Ru(C≡C-cyclo-3-C4H3S)2{P(OEt)3}4] (5) featuring the 3-thienyl moiety as a surface contacting group for gold electrodes have been prepared, crystallographically characterised in the case of 3–5 and studied in metal|molecule|metal junctions by using both scanning tunnelling microscope break-junction (STM-BJ) and STM-I(s) methods (measuring the tunnelling current (I) as a function of distance (s)). The compounds exhibit similar conductance profiles, with a low conductance feature being more readily identified by STM-I(s) methods, and a higher feature by the STM-BJ method. The lower conductance feature was further characterised by analysis using an unsupervised, automated multi-parameter vector classification (MPVC) of the conductance traces. The combination of similarly structured HOMOs and non-resonant tunnelling mechanism accounts for the remarkably similar conductance values across the chemically distinct members of the family 2–5.
- Bock, S?ren,Al-Owaedi, Oday A.,Eaves, Samantha G.,Milan, David C.,Lemmer, Mario,Skelton, Brian W.,Osorio, Henrry M.,Nichols, Richard J.,Higgins, Simon J.,Cea, Pilar,Long, Nicholas J.,Albrecht, Tim,Martín, Santiago,Lambert, Colin J.,Low, Paul J.
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Read Online
- Synthesis and Photochemical Application of Hydrofluoroolefin (HFO) Based Fluoroalkyl Building Block
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A novel fluoroalkyl iodide was synthesized on multigram scale from refrigerant gas HFO-1234yf as cheap industrial starting material in a simple, solvent-free, and easily scalable process. We demonstrated its applicability in a metal-free photocatalytic ATRA reaction to synthesize valuable fluoroalkylated vinyl iodides and proved the straightforward transformability of the products in cross-coupling chemistry to obtain conjugated systems.
- Varga, Bálint,Tóth, Balázs L.,Béke, Ferenc,Csenki, János T.,Kotschy, András,Novák, Zoltán
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supporting information
p. 4925 - 4929
(2021/07/01)
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- Synthesis of Phenanthrenes via Palladium-Catalyzed Three-Component Domino Reaction of Aryl Iodides, Internal Alkynes, and o-Bromobenzoic Acids
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A new palladium-catalyzed domino alkyne insertion/C-H activation/decarboxylation sequence has been developed, which provides an efficient approach for synthesizing a variety of functionalized phenanthrenes in moderate to good yields. The method shows broad substrate scope and good functional group tolerance by employing readily available materials, including aryl iodides, internal alkynes, and o-bromobenzoic acids, as three-component coupling partners.
- Deng, Guobo,Liang, Yun,Luo, Xiai,Yang, Xiumei,Yang, Yuan,Yang, Yuzhong,Zhou, Liwei
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supporting information
p. 1223 - 1230
(2020/04/15)
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- Preparation and Reactions of Mono- and Bis-Pivaloyloxyzinc Acetylides
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Mono-pivaloyloxyzinc acetylide and bis-pivaloyloxyzinc acetylide were selectively prepared from ethynylmagnesium bromide in quantitative yields. These zinc reagents readily underwent Negishi cross-couplings with (hetero)aryl iodides or bromides as well as subsequent Sonogashira cross-couplings. 1,3-Dipolar cycloadditions of these zinc acetylides with benzylic azides produced zincated and bis-zincated triazoles which were trapped with several electrophiles. An opposite regioselectivity compared to the Cu-catalyzed click-reactions was observed.
- Tüllmann, Carl Phillip,Chen, Yi-Hung,Schuster, Robin J.,Knochel, Paul
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supporting information
p. 4601 - 4605
(2018/08/09)
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- Intermolecular Desymmetrizing Gold-Catalyzed Yne–Yne Reaction of Push–Pull Diarylalkynes
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Push–pull diaryl alkynes are dimerized in the presence of a cationic gold catalyst. The polarized structure of the applied starting materials enables the generation of a highly reactive vinyl cation intermediate in an intermolecular reaction. Trapping of the vinyl cation by a nucleophilic attack of the electron-poor aryl unit then leads to the selective formation of highly substituted naphthalenes in a single step and in complete atom economy.
- Weingand, Vanessa,Wurm, Thomas,Vethacke, Vanessa,Dietl, Martin C.,Ehjeij, Daniel,Rudolph, Matthias,Rominger, Frank,Xie, Jin,Hashmi, A. Stephen K.
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supporting information
p. 3725 - 3728
(2018/02/23)
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- Gold-Catalyzed Dimerization of Diarylalkynes: Direct Access to Azulenes
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We have developed a simple gold-catalyzed procedure for the synthesis of substituted and modifiable azulenes. The azulenes are formed either by the dimerization of push–pull diarylalkynes bearing a fluorine atom in ortho or para position or by the dimeriz
- Claus, Vanessa,Schukin, Michael,Harrer, Siegfried,Rudolph, Matthias,Rominger, Frank,Asiri, Abdullah M.,Xie, Jin,Hashmi, A. Stephen K.
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supporting information
p. 12966 - 12970
(2018/09/25)
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- Na2S-mediated synthesis of terminal alkynes from: Gem -dibromoalkenes
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The Na2S-mediated facile synthesis of terminal alkynes from gem-dibromoalkenes, at 20/40 °C under open flask conditions has been developed. Various precursors derived from heteroaromatic/aromatic/aliphatic aldehydes were found compatible. The reaction is proposed to proceed through the Fritsch-Buttenberg-Wiechell (FBW) rearrangement involving the corresponding vinyl carbene. Using mild reaction conditions with inexpensive Na2S·9H2O under air atmosphere has significant advantages over earlier routes.
- Singh, Radhey M.,Nandini, Durgesh,Bharadwaj, Kishor Chandra,Gupta, Tanu,Singh, Raj Pal
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supporting information
p. 9979 - 9982
(2017/12/26)
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- Reaction discovery using acetylene gas as the chemical feedstock accelerated by the stop-flow micro-tubing reactor system
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Acetylene gas has been applied as a feedstock under transition-metal catalysis and photo-redox conditions to produce important chemicals including terminal alkynes, fulvenes, and fluorinated styrene compounds. The reaction discovery process was accelerated through the use of stop-flow micro-tubing reactors. This reactor prototype was developed by joining elements from both continuous micro-flow and conventional batch reactors, which was convenient and effective for gas/liquid reaction screening. Notably, the developed transformations were either inefficient or unsuccessful in conventional batch reactors. Its success relies on the unique advantages provided by this stop-flow micro-tubing reactor system.
- Xue, Fei,Deng, Hongping,Xue, Chengwen,Mohamed, Dara Khairunnisa Binte,Tang, Karen Yuanting,Wu, Jie
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p. 3623 - 3627
(2017/07/11)
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- Synthesis of Graphene Nanoribbons by Ambient-Pressure Chemical Vapor Deposition and Device Integration
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Graphene nanoribbons (GNRs), quasi-one-dimensional graphene strips, have shown great potential for nanoscale electronics, optoelectronics, and photonics. Atomically precise GNRs can be bottom-up synthesized by surface-assisted assembly of molecular building blocks under ultra-high-vacuum conditions. However, large-scale and efficient synthesis of such GNRs at low cost remains a significant challenge. Here we report an efficient bottom-up chemical vapor deposition (CVD) process for inexpensive and high-throughput growth of structurally defined GNRs with varying structures under ambient-pressure conditions. The high quality of our CVD-grown GNRs is validated by a combination of different spectroscopic and microscopic characterizations. Facile, large-area transfer of GNRs onto insulating substrates and subsequent device fabrication demonstrate their promising potential as semiconducting materials, exhibiting high current on/off ratios up to 6000 in field-effect transistor devices. This value is 3 orders of magnitude higher than values reported so far for other thin-film transistors of structurally defined GNRs. Notably, on-surface mass spectrometry analyses of polymer precursors provide unprecedented evidence for the chemical structures of the resulting GNRs, especially the heteroatom doping and heterojunctions. These results pave the way toward the scalable and controllable growth of GNRs for future applications.
- Chen, Zongping,Zhang, Wen,Palma, Carlos-Andres,Lodi Rizzini, Alberto,Liu, Bilu,Abbas, Ahmad,Richter, Nils,Martini, Leonardo,Wang, Xiao-Ye,Cavani, Nicola,Lu, Hao,Mishra, Neeraj,Coletti, Camilla,Berger, Reinhard,Klappenberger, Florian,Kl?ui, Mathias,Candini, Andrea,Affronte, Marco,Zhou, Chongwu,De Renzi, Valentina,Del Pennino, Umberto,Barth, Johannes V.,R?der, Hans Joachim,Narita, Akimitsu,Feng, Xinliang,Müllen, Klaus
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supporting information
p. 15488 - 15496
(2016/12/07)
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- Cu(ii)@Luviset clear as recyclable catalyst for the formation of C-C bond in homo-coupling of terminal alkynes
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Commercial copolymer Luviset clear (L1), an environmentally benign and efficient ligand, was used to facilitate the catalytic performance of Cu(NO3)2 for homo-coupling of terminal alkynes. A series of substituted aromatic and aliphat
- Wang, Zheng-Jun,Wang, Peng-Hui,Lv, Jing-Jing,Feng, Jiu-Ju,Xu, Xinhua,Wang, Ai-Jun,Au, Chak-Tong,Qiu, Renhua
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p. 96372 - 96376
(2015/11/24)
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- Aerobic oxynitration of alkynes with tBuONO and TEMPO
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An efficient method for stereoselective nitroaminoxylation of alkyne has been reported. The reaction enjoys a broad substrate scope, good functional group tolerance, and high yields. Synthetically useful α-nitroketones can be accessed through these products in a single step.
- Dutta, Uttam,Maity, Soham,Kancherla, Rajesh,Maiti, Debabrata
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supporting information
p. 6302 - 6305
(2015/02/19)
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- Regio- and stereoselective dimerization of arylacetylenes and optical and electrochemical studies of (E)-1,3-enynes
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The N-heterocyclic carbene palladium complex (SIPr)Pd(cinnamyl)Cl [SIPr=N,N'-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene) promotes regio- and stereospecific dimerization of a variety of arylalkynes to give (E)-1,3-enynes in good to excellent yields. An efficient and practical procedure for their synthesis was developed using a biphasic aqueous alkali/heptane system. Optical and electronic properties of (E)-1,3-enynes are highly tunable. Depending on the nature of the substituents, HOMO energies vary in the range 5.3-6.0eV. (E)-1,3-Enynes can exhibit intense photoluminescence in the spectral region 350-500nm.
- Morozov, Oleg S.,Asachenko, Andrey F.,Antonov, Denis V.,Kochurov, Vitaly S.,Paraschuk, Dmitry Yu.,Nechaev, Mikhail S.
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supporting information
p. 2671 - 2678
(2014/09/29)
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- Synthesis and properties of new 9,10-anthraquinone derived compounds for molecular electronics
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Fourteen new derivatives of 9,10-anthraquinone or 9,10-dimethoxyanthracene were designed, synthesised and characterised. Regarding the structure, the compounds are π-conjugated (cross and linear, respectively) and feature thiophene terminated side arms attached to five different positions of the anthraquinone or anthracene core. The synthesis of the compounds involves a cross-coupling procedure in the key reaction steps. Crystal structures of compounds 5 and 19 have been studied. The thiophene containing title compounds 1-5 can be reduced and oxidised by a two step redox process. The electrochemical parameters have been analysed by cyclic voltammetry (CV). Theoretical calculations in the framework of all-electron density functional theory (DFT) were used to investigate the electronic structure of the individual free molecules. Furthermore, calculations of the transport properties of model devices containing compounds 1-3 and respective reduced hydroquinone derivatives assembled at Au(111) electrodes were carried out to evaluate their potential for the application as redox-active switches.
- Seidel, Nadine,Hahn, Torsten,Liebing, Simon,Seichter, Wilhelm,Kortus, Jens,Weber, Edwin
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p. 601 - 610
(2013/04/10)
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- Gold-catalyzed oxazoles synthesis and their relevant antiproliferative activities
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Nine 5-aryl-2-methyloxazole derivatives were synthesized via gold-catalyzed alkyne oxidation. All of the compounds have been screened for their antiproliferative activities against MCF-7 cell (human breast carcinoma), A549 cell (human lung carcinoma) and
- Wu, Chao,Liang, Zhi-Wu,Xu, Ying-Ying,He, Wei-Min,Xiang, Jian-Nan
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p. 1064 - 1066
(2014/01/06)
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- One-pot, two-step conversion of aldehydes to phosphonyl- and sulfonylpyrazoles using Bestmann-Ohira reagent
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A one-pot, two-step, three-component method for the conversion of commercially available aldehydes to phosphonylpyrazoles has been developed, demonstrating, for the first time, the dual reactivity of the Bestmann-Ohira reagent (BOR) in a single-pot transformation. This method, extended to the synthesis of sulfonylpyrazoles by employing BOR in the first step and a diazomethyl sulfone in the second step, is complementary, with regard to regioselectivity, to the previous methods for the synthesis of such functionalized pyrazoles.
- Kumar, Rahul,Verma, Deepti,Mobin, Shaikh M.,Namboothiri, Irishi N. N.
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supporting information; experimental part
p. 4070 - 4073
(2012/09/21)
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- One-pot desilylation/dimerization of terminal alkynes by ruthenium and acid-promoted (RAP) catalysis
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The dimerization of terminal arylalkynes promoted by the (p-cymene)ruthenium dichloride dimer/acetic acid system {[RuCl 2(p-cymene)]2/AcOH} can be performed starting from the trimethylsilylethynyl derivatives (12 substrates), deprotected in situ, to afford 1,4-disubstituted 1-en-3-ynes with high regio- and (E)-stereoselectivity, at room temperature. The extension of this unprecedented two-reaction sequence to a diyne substrate affords a fluorene-based conjugated oligomer. The reaction mixture resulting from the desylilation-dimerization process dimerizes additional aliquots of phenylacetylene. The one-pot protocol results in shorter reaction times due to the presence of acetate salts which increase the concentration of active catalytic species, in which the acetate ligand acts as base toward the bound alkyne. The ruthenium source is transformed into a new trihapto-hexa-1,3-dien-5-yn-3-yl complex, formed by metal-assisted coupling of the enyne product and the terminal alkyne, and still maintaining catalytic activity. Selectivity, endurance, medium and functional group compatibility are the key features of the catalytic system obtained from the p-cymene ruthenium dimer under the one-pot conditions.
- Pasquini, Chiara,Bassetti, Mauro
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supporting information; experimental part
p. 2405 - 2410
(2010/12/29)
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- Terminal alkynes from aldehydes via dehydrohalogenation of (Z)-1-iodo-1-alkenes with TBAF
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Terminal alkynes were prepared in near quantitative yields via dehydrohalogenation of (Z)-1-iodo-1-alkenes with tetrabutylammonium fluoride (TBAF) under mild conditions. The methodology was expanded to include a one-pot, direct synthesis of terminal alkynes from aldehydes without the necessity of isolating and purifying the intermediate iodoalkene.
- Beshai, Mira,Dhudshia, Bhartesh,Mills, Ryan,Thadani, Avinash N.
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supporting information; experimental part
p. 6794 - 6796
(2009/04/07)
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- Novel 3-phenylprop-2-ynylamines as inhibitors of mammalian squalene epoxidase.
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The synthesis of a novel series of 3-phenylprop-2-ynylamines as selective mammalian squalene epoxidase inhibitors is described. Structure activity relationship studies led to the discovery of compound 19, 1-[3-(3,5-dichlorophenyl)-prop-2-ynyl]-3- methylpiperidine hydrochloride with an IC50 of 2.8 +/- 0.6 microM against rat liver squalene epoxidase. Against 23 strains of fungal squalene epoxidase compound 19 was found to be inactive.
- Musso, David L,Clarke, Morris J,Kelley, James L,Boswell, G Evan,Chen, Grace
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p. 498 - 506
(2007/10/03)
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- Thermal behavior of diynes with formally conjugated heteroaromatic sidegroups
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Diynes with heteroaromatic sidegroups directly linked to the acetylenic backbone were found to show liquid crystalline behaviour upon heating. Thus, 1,4-di(2-thienyl)-1,3-butadiyne, 1,4-di(3-thienyl)-1,3-butadiyne, 1,4-di(3- benzo[b]thienyl)-1,3-butadiyne, 1-(3-quinolyl)-4-(2-thienyl)-1,3-butadiyne, 1-(3-quinolyl)-4-(3-thienyl)-1,3-butadiyne, and 5-(2-thienyl)-2,4-pentadiyne- 1-ol were investigated for their thermal behavior. These diynes also underwent polymerization in their liquid crystalline state, although the polymers so formed did not show liquid crystalline behavior. It was found that the S-atom of the heteroaromatic moieties tends to play a role in making the diynes show liquid crystalline behavior. Differential scanning calorimetry, thermogravimetric analysis and hot stage microscopy were used to investigate the liquid crystalline nature of the diynes. All of them showed a nematic liquid crystalline phase upon annealing, whereas smectic phase was totally absent.
- Sarkar, Abhijit,Talwar, Satya S.
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p. 859 - 864
(2007/10/03)
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- Heteroaryl functionalised diacetylenes: Preparation and solid-state reactivity
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Diacetylenes are known to undergo solid-state topochemical polymerisation to give polydiacetylenes. The reactivity of the monomer is controlled by the arrangement of the molecules in the crystal lattice wherein certain parametric conditions must be met for 1,4-addition to proceed. In the present paper, we investigated the structure-reactivity relationship of a class of diacetylene monomers. Heteroaryl moieties such as thiophene, benzo[b]thiophene and quinoline as one or both directly bound side groups of a diacetylene backbone were used. Thus various symmetrical as well as unsymmetrical diacetylenes were prepared and characterised. The solid-state polymerisation behaviour of these diacetylenes was studied in the light of their single-crystal X-ray structure. It was found that in order to react in the solid state, the diacetylenes must have the required lattice parameters. However, even when the required lattice parameters are met, the diacetylene monomers do not necessarily undergo solid-state 1,4-addition polymerisation, implying the existence of further controlling factors to determine reactivity.
- Sarkar, Abhijit,Talwar, Satya S.
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p. 4141 - 4146
(2007/10/03)
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- An improved procedure for the preparation of aryl- and hetarylacetylenes
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A number of relatively volatile acetylenes RC ≡ CH (R = aryl or hetaryl) have been prepared with high yields by heating a mixture of the corresponding alcohols RC ≡ CC(CH3)2OH and paraffin oil with small amounts of powdered potassium hydroxide in vacuum. The alcohols were obtained by Pd/Cu-catalyzed cross coupling of aryl or hetaryl halides RX (X = Br, in one case I) with the commercially available HC ≡ CC(CH3)2OH.
- Mal'Kina,Brandsma,Vasilevsky,Trofimov
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p. 589 - 590
(2007/10/03)
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- Flash Vacuum Pyrolysis of Stabilised Phosphorus Ylides. Part 2. Two-step Conversion of Acid Chlorides into Acetylenic Esters and Terminal Alkynes
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The known thermal extrusion of Ph3PO from α-acyl-α-ethoxycarbonyl ylides 1 to give acetylenic esters 2 can be accomplished in excellent yield by using flash vacuum (FVP) at 500 deg C.Upon rasing the furnace temperature to 750 deg C, this reaction is accompanied by unexpected loss of the ethoxycarbonyl group to give the terminal alkynes 7 in moderate yield.A mechanism is proposed for this reaction based on isotopic labelling studies.Ten new examples of ylides 1 have been prepared for the first time.
- Aitken, R. Alan,Horsburg, Caroline E. R.,McCreadie, J. Graeme,Seth, Shirley
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p. 1727 - 1732
(2007/10/02)
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- Electronic Structure of Ethynylthiophenes
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He I and He II photoelectron spectra of all isomeric mono- and diethynylthiophenes were recorded.The electronic structure was analyzed and spectra assigned on the basis of empirical considerations and semiempirical MO calculations.The spectra indicate various interactions taking place between thiophene ? and ethynyl ? orbitals.The relationship between deduced electronic structure and formation of novel polymer materials is discussed.
- Novak, Igor,Ng, Siu Choon,Fang, Jiye,Mok, Chup Yew,Huang, Hsing Hua
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p. 748 - 751
(2007/10/02)
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- Application of Phase Transfer Catalysis, 14.- Preparation of Alkynes from Halides with Solid Potassium tert-Butoxide and Crown Ether
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Preparatively very simple and mild HX eliminations with solid potassium tert-butoxide in petroleum ether in the presence of catalytic amounts of crown-6 are described. 1,2-Dihalides (from alkenes) and 1,1-dihalides (from aldehydes) yield 1-alkynes; internal geminal dihalides (from symmetric ketones) give internal alkynes in excellent yields. 2,2-Dihalides (from methyl ketones) yield homogeneous 1-alkynes only if the 3-position is blocked. (E)-Haloalkenes lead also to alkynes in a syn-elimination process.
- Dehmlow, Eckehard V.,Lissel, Manfred
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