- Preparation of diynes via selective bisalkynylation of zirconacycles
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Reaction of alkynyl halides with in situ prepared zirconacyclopentanes, -pentenes, and -pentadienes in the presence of CuCl under mild reaction conditions afforded alkynes or diynes. Control of the reaction conditions selectively afforded monoalkynylation products of zirconacycles. Reaction of zirconacycles with 2 equiv of alkynyl halides resulted in the formation of diynes. Selective monoalkynylation of zirconacycle with an alkynyl halide, followed by reaction with a different alkynyl halide, afforded unsymmetrical diynes. Bisalkynylation product of zirconacyclopentadiene was gradually converted into a tricyclic compound.
- Liu,Xi,Hara,Nakajima,Yamazaki,Kotora,Takahashi
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Read Online
- Allene formation by the reaction of olefins with propargyl silyl ethers mediated by a zirconocene complex
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Ethylene and styrene derivatives reacted with various propargylic ethers in the presence of zirconocene(II) to afford allenic products in high yields. The reaction proceeded via formation of zirconacyclopentenes by selective coupling of an olefin and a propargylic ether, which was followed by β-elimination of the siloxy group. Deuterolysis confirmed that the final product had a zirconium-carbon bond.
- Takahashi, Tamotsu,Hara, Ryuichiro,Huo, Shouquan,Ura, Yasuyuki,Leese, Mathew P.,Suzuki, Noriyuki
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Read Online
- Electrochemical Reduction and Intramolecular Cyclization of 1-Iodo-5-decyne and 1-Bromo-5-decyne at Vitreous Carbon Cathodes in Dimethylformamide
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In dimethylformamide containing tetramethylammonium perchlorate, cyclic voltammograms for reduction of 1-iodo-5-decyne and 1-bromo-5-decyne at a vitreous carbon electrode each consist of a single irreversible wave due to two-electron scission of the carbon-halogen bond.Preparative-scale electrolyses of 1-iodo-5-decyne yield pentylidenecyclopentane, 5-decyne, 1-decen-5-yne, and a small amount of 5-decyn-1-ol, whereas reduction of 1-bromo-5-decyne affords mainly 5-decyne and 1-decen-5-yne along with a modest quantity of pentylidenecyclopentane.Differences in product distributions correlate with the extent to which the 5-decyn-1-yl radical persists as a transient species.Pentylidenecyclopentane arises via intramolecular cyclization of the 5-decyn-1-yl radical followed by hydrogen atom abstraction, 5-decyne is formed via protonation of the 5-decyn-1-yl carbanion by either water or the tetramethylammonium cation, and 1-decen-5-yne and 5-decyn-1-ol are obtained, respectively, via E2 and SN2 reactions between unreduced starting material and hydroxide ion (generated by deprotonation of water).In the presence of a proton donor (diethyl malonate or hexafluoroisopropyl alcohol), the quantities of pentylidenecyclopentane and 5-decyne rise noticeably and the yield of 1-decen-5-yne falls dramatically.
- Shao, Rui-lian,Peters, Dennis G.
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Read Online
- 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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- Rh(III)-Catalyzed [5 + 2] Oxidative Annulation of Cyclic Arylguanidines and Alkynes to 1,3-Benzodiazepines. A Striking Mechanistic Proposal from DFT
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A novel and mild Rh(III)-catalyzed [5 + 2] oxidative annulation between cyclic arylguanidines and alkynes efficiently affords 1,3-benzodiazepines (pentacyclic guanidines). The use of O2 as the sole oxidant in place of commonly used metal oxidants such as AgOAc clearly improves the efficiency of the oxidative annulation process. The mechanism of the cycloaddition most likely involves the formation of an eight-membered rhodacycle. DFT calculations support a striking mechanistic proposal for the [5 + 2] oxidative annulation.
- Martínez-Yá?ez, Nuria,Suárez, Jaime,Cajaraville, Ana,Varela, Jesús A.,Saá, Carlos
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supporting information
p. 1779 - 1783
(2019/03/29)
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- Dehalogenation of vicinal dihalo compounds by 1,1′-bis(trimethylsilyl)-1: H,1′ H-4,4′-bipyridinylidene for giving alkenes and alkynes in a salt-free manner
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We report a transition metal-free dehalogenation of vicinal dihalo compounds by 1,1′-bis(trimethylsilyl)-1H,1′H-4,4′-bipyridinylidene (1) under mild conditions, in which trimethylsilyl halide and 4,4′-bipyridine were generated as byproducts. The synthetic protocol for this dehalogenation reaction was effective for a wide scope of dibromo compounds as substrates while keeping the various functional groups intact. Furthermore, the reduction of vicinal dichloro alkanes and vicinal dibromo alkenes also proceeded in a salt-free manner to afford the corresponding alkenes and alkynes.
- Rej, Supriya,Pramanik, Suman,Tsurugi, Hayato,Mashima, Kazushi
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supporting information
p. 13157 - 13160
(2017/12/26)
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- Arylsulfonylacetylenes as alkynylating reagents
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The unexpected anti-Michael addition of RLi to β-substituted sulfonylacetylenes, followed by in situ elimination of the ion sulfinate, allows the alkynylation of C(sp2) and C(sp3). Aryl and heteroaryl acetylenes, enynes, and mono and dialkyl alkynes can be obtained in very high yields under very mild conditions, avoiding the use of transition metals as catalysts and, in many cases, haloderivatives as starting materials. Furthermore, the use of lithium 2-p-tolylsulfinyl benzylcarbanions as nucleophiles of these reactions allows their stereocontrolled alkynylation, affording enantiomerically pure alkynes or enantioenriched allenes depending on the protonating agent (NH4Cl or H2O).
- Marzo, Leyre,Aleman, Jose,Garcia Ruano, Jose Luis
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p. 403 - 407
(2013/07/26)
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- Expanding the scope of arylsulfonylacetylenes as alkynylating reagents and mechanistic insights in the formation of Csp2-Csp and Csp 3-Csp bonds from organolithiums
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We describe the unexpected behavior of the arylsulfonylacetylenes, which suffer an "anti-Michael" addition of organolithiums producing their alkynylation under very mild conditions. The broad scope, excellent yields, and simplicity of the experimental procedure are the main features of this methodology. A rational explanation of all these results can be achieved by theoretical calculations, which suggest that the association of the organolithiums to the electrophile is a previous step of their intramolecular attack and is responsible for the unexpected "anti-Michael" reactions observed for substituted sulfonylacetylenes. A calculated conclusion: A new transition-metal-free strategy for the synthesis of any kind of alkynyl derivatives in high yields in the reaction of organolithium species with arylsulfonylacetylenes is presented (see scheme). Theoretical calculations provide a rational explanation and suggest that association of the organolithium to the electrophile is a previous step of their intramolecular attack and is responsible for the "anti-Michael" reaction. Copyright
- Garcia Ruano, Jose Luis,Aleman, Jose,Marzo, Leyre,Alvarado, Cuauhtemoc,Tortosa, Mariola,Diaz-Tendero, Sergio,Fraile, Alberto
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supporting information; experimental part
p. 8414 - 8422
(2012/07/27)
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- Effect of solvent and temperature on the lithium?bromine exchange of vinyl bromides: Reactions of n -butyllithium and t -butyllithium with (E)-5-bromo-5-decene
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The outcome of reactions of (E)-5-bromo-5-decene (1), a representative vinyl bromide, with t-BuLi or n-BuLi at 0 °C and room temperature, respectively, in a variety of solvent systems has been investigated. Vinyl bromide 1 does not react with t-BuLi in pure heptane; however, the presence of even small quantities of an ether in a predominantly heptane medium resulted in virtually complete consumption of 1 at 0 °C, resulting in nearly the same distribution of products, including 60?80% of (Z)-5-decenyllithium, regardless of the solvent composition. Vinyl bromide 1 reacts slowly with n-BuLi at room temperature in a variety of ether and heptane-ether mixtures to afford a mixture of products including significant quantities of recovered starting material. The results of these experiments demonstrate that lithium?bromine exchange between a vinyl bromide and either t-BuLi or n-BuLi at temperatures significantly above ?78 °C is not an efficient method for the generation of a vinyllithium.
- Bailey, William F.,Luderer, Mark R.,Uccello, Daniel P.,Bartelson, Ashley L.
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experimental part
p. 2661 - 2666
(2010/08/19)
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- Selective terminal alkyne metathesis: Synthesis and use of a unique triple bonded dinuclear tungsten alkoxy complex containing a hemilabile ligand
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The in situ synthesis of new alkyne metathesis catalysts is described, with particular emphasis on the search for tris-alkoxytungsten-based terminal alkyne metathesis. In that context, hemilabile, ether-containing alkoxy ligands have proved to be suitable and have led to the design and use of a sterically hindered hemilable ligand for the synthesis of a well-defined binuclear, triple-bonded W ≡ W complex. This complex is shown to be a highly active and selective catalyst precursor for terminal alkyne metathesis, and allows the unprecedented metathesis of phenylacetylene.
- Coutelier, Olivier,Nowogrocki, Guy,Paul, Jean-Francois,Mortreux, Andre
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p. 2259 - 2263
(2008/09/19)
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- Catalytic reduction and intramolecular cyclization of haloalkynes in the presence of nickel(I) salen electrogenerated at carbon cathodes in dimethylformamide
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Pentylidenecyclopentane can be conveniently prepared in up to 86% yield via the catalytic reduction of 1-iodo- or 1-bromo-5-decyne by [[2,2′-[1,2- ethanediylbis(nitrilomethylidyne)]bis[phenolato]]-N,N′,O,O′] -nickelate(I) electrogenerated at a carbon cathode in dimethylformamide containing tetramethylamnionium tetrafluoroborate. This electrosynthesis can be accomplished at potentials for which the haloalkynes are electroinactive, and it can be completed within 30 min at room temperature. Attempts to synthesize pentylidenecyclobutane and pentylidenecyclohexane from 1-halo-4-nonynes and 11-halo-5-undecynes, respectively, under similar conditions afford the carbocycles in very low yields (2% and 6%, respectively), Other products derived from the various haloalkynes are dimers, alkynes, and 1-alkenynes. Dimers (alkadiynes) arising From 1-halo-4-nonynes and 11-halo-5-undecynes are formed in yields ranging from 80% to 89%, whereas icosa-5, 15-diyne (the dimer obtained from a 1-halo-5-decyne) is found in significantly lower yield (≤ 13%). Alkynes and 1-alkenynes are produced in yields of 3-10% and 2-3%, respectively. A mechanistic scheme, involving alkyn-1-yl radicals arising from niekel(I) salon catalyzed cleavage of the carbon-halogen bond of each haloalkyne, is proposed to account for the formation of all products.
- Ischay, Michael A.,Mubarak, Muhammad S.,Peters, Dennis G.
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p. 623 - 628
(2007/10/03)
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- Transformation of β-chalcogeno alkenylboranes into tetrasubstituted olefins
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In view of generating trisubstituted vinylic chalcogen derivatives, β-chalcogeno alkenylboranes generated through the chalcogen electrophile induced rearrangements of 1-alkynyltrialkyl borates have been subjected to Suzuki-Miyaura coupling and to boron to copper transmetalation followed by alkylation. Some of the trisubstituted vinyl sulfides obtained by this latter strategy have been converted efficiently into the title olefins through the NiCl2(dmpe) catalyzed coupling with various Grignard reagents.
- Gerard, Julien,Hevesi, László
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p. 367 - 381
(2007/10/03)
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- A Novel Transformation of Esters to Alkynes with 1-Substituted Benzotriazoles
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Reactions of lithio benzotriazol-1-yl derivatives 2, 11, and 25 with aromatic and aliphatic esters 3, 12, and 26 gave α-(benzotriazol-l-yl) ketones 4, 13, and 27, respectively, in high yields. Alternatively, α-(benzotriazol-l-yl) ketones 22 can be accessed by the reaction of α-(benzotriazol-1-yl) esters 20 with Grignard reagents. Condensation of 4, 13, 22, and 27 with (p-toluenesulfonyl)hydrazine provided p-tosylhydrazones 5, 14, 21, and 28. Treatment of hydrazones 5, 21, and 28 with n-butyllithium in diethyl ether resulted in the elimination of the tosyl group, dinitrogen, and benzotriazolyl group to afford the corresponding acetylenes 9, 23, and 29 in good yields. When α-(benzotriazol-l-yl) 1-α-phenoxy hydrazones 14 were treated with methyllithium, n-butyllithium, or phenyllithium, alkynes 18 were obtained, in which phenoxy groups were replaced by the lithium reagents.
- Katritzky, Alan R.,Wang, Jin,Karodia, Nazira,Li, Jianqing
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p. 4142 - 4147
(2007/10/03)
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- Evidence for reversible ylide formation: Equilibrium between free alkylidenecarbenes and ethereal solvent-alkylidenecarbene complexes (oxonium ylides)
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The free alkylidenecarbene, 2-butyl-1-hexenylidene 1 (R = Bu), generated by triethylamine-induced α-elimination of 2-butyl-1-hexenyliodonium tetrafluoroborate 7 in tetrahydrofuran undergoes regioselective 1,5-C-H insertions, 1,2-shifts of the butyl group, and electrophilic attack on the tertiary amine followed by protonation to give the cyclopentene 8, the alkyne 9, and the vinylammonium salt 10, respectively. In addition to these free carbene-derived products, the reaction affords the three-component coupling product, the vinyl ether 11, produced through nucleophilic attack of tetrahydrofuran on 1 (R = Bu) generating the oxonium ylide 2 (R = Bu), followed by protonation with subsequent ring-opening of the resulting cyclic oxonium salt 15 (R = Bu) by nucleophilic attack of triethylamine. Reactions were observed to be temperature dependent, as reflected in variations in the product profiles: decreasing the reaction temperature tended to decrease the yields of free alkylidenecarbene-derived products, i.e., cyclopentenes alkynes, and vinylammonium salts, and to increase those of the vinyloxonium ylide-derived products, vinyl ethers. This temperature dependence is explained in terms of reversible oxonium ylide formation. No evidence was observed to suggest the existence of an equilibrium between the free alkylidenecarbene and the sulfonium ylide in the reaction in tetrahydrothiophene. These results are consistent with quantum calculations using the MOPAC 93 program.
- Sueda, Takuya,Nagaoka, Takema,Goto, Satoru,Ochiai, Masahito
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p. 10141 - 10149
(2007/10/03)
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- Cyclizations during the Grignard Reactions of ω-Bromoalkynes
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The Grignard reactions of a number of ω-bromoalkynes have been shown to undergo regioselective cyclizations in certain instances to give the smaller possible carbocycle. These cyclizations are shown to result from two competing processes, whose relative efficiencies depend upon the chain length and the remote substitutent on the acetylene. These are interpreted as a radical cyclization which occurs only during the time the Grignard is being formed from the bromide and an organometallic reaction which slowly transforms the Grignard reagent into its cyclic isomer. The mechanistic details of these transformations are discussed.
- Crandall, Jack K.,Michaely, William J.,Collonges, Francois,Nelson, Deanna J.,Ayers, Timothy A.,Gajewski, Joseph J.
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p. 1473 - 1490
(2007/10/03)
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- Reactions of some alkynyl halides with samarium(II) iodide
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Certain alkynyl halides (6-halo-1-ynes) react with samarium(II) iodide (SmI2) to give cyclized products (methylenecyclopentanes) in good yield. We have found some interesting evidence for the presence of radical and unstable organosamarium intermediates in these reductive cyclizations. Methyl 7-halohept-2-ynoates are not, however, good substrates for this cyclization methodology.
- Zhou, Zhihong,Larouche, Denis,Bennett, Sharon M.
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p. 11623 - 11644
(2007/10/02)
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- Flash Vacuum Pyrolysis of Stabilised Phosphorus Ylides. Part 1. Preparation of Aliphatic and Therminal Alkynes
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Thermal extrusion of Ph3PO from β-oxoalkylidenetriphenylphosphoranes 4 to give the alkynes 5, which under conventional pyrolysis conditions is restricted to cases in which R1 is an electron withdrawing group, has been successfully achieved for R1=H or alkyl by using FVP.The method allows convenient construction of multigram quantities of the alkynes 5 from alkyl halides 1 and allows convenient construction of multigram quantities of the alkynes 5 from alkyl halides 1 and acid chlorides 3 in three steps with good overall yields.Under the conditions used the ylides with R2 = cyclobutyl also undergo less of ethene to provide convenient access to the vinylalkynes 6.
- Aitken, R. Alan,Atherton, J. Ian
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p. 1281 - 1284
(2007/10/02)
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- PREPARATION AND FACILE CYCLIZATION OF 5-ALKYN-1-YLLITHIUMS
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Primary 5-hexyn-1-yllithiums, which may be generated in virtually quantitative yield by low-temperature lithium-iodine interchange, undergo regiospecific 5-exo-dig cyclization via stereoselectively syn-addition of CH2Li to the alkyne moiety to give vinyllithiums that may be trapped with any of a variety of electrophiles to deliver functionalized cyclopentylidene-containing products.
- Bailey, William F.,Ovaska, Timo V.,Leipert, Thomas K.
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p. 3901 - 3904
(2007/10/02)
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- Methyl Group Migration in the Reactions of Alkynyltrialkylborates
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It is shown that the methyl group cannot be used as a cheap, non-migrating group in the reactions of alkynyltrialkylborates with electrophiles.However, trimethylborane can be used as a methylboronating agent for alkynes, given the right choice of solvent, and this may be of use in terpene synthesis.
- Pelter, Andrew,Drake, Robert A.
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p. 4181 - 4184
(2007/10/02)
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- Vinylic Organoboranes. 1. A Convenient Synthesis of Acetylenes via the Reaction of Lithium (1-Alkynyl)organoborates with Iodine
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Lithium (1-alkynyl)organoborates, readily prepared from organoboranes and lithium acetylides, undergo a facile reaction at low temperature with iodine to for internal acetylenes in high yield.Unlike conventional methods for the preparation of acetylenes via nucleophilic displacement, the reaction is applicable to both primary and secondary as well as aromatic and functionally substituted groups.The use of lithium acetylide-ethylenediamine form the formation of the organoborate extends the reaction to terminal acetylenes.This reaction occurs with complete retention of the configuration about the boron-carbon bond.The procedure, with its exceptionally broad applicability, provides a simple, general route to internal and terminal acetylenes.
- Suzuki, Akira,Miyaura, Norio,Abiko, Shigeo,Itoh, Mitsuomi,Midland, M., Mark,et al.
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p. 4507 - 4511
(2007/10/02)
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- A New General Synthesis of Aliphatic and Terminal Alkynes: Flash Vacuum Pyrolysis of β-Oxoalkylidenetriphenylphosphoranes
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By using flash vacuum conditions the thermal elimination of Ph3PO from β-oxoalkylidenetriphenylphosphoranes, previously confined to cases with an α-electron withdrawing group, has been extended to provide a general, high yielding synthesis of aliphatic and terminal alkynes.
- Aitken, R. Alan,Atherton, J. Ian
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p. 1140 - 1141
(2007/10/02)
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- Cyclizations of ω-Alkynyl Halides by Cr(II) Reduction
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Reduction of halides of the types RCC(CH2)nX with Cr(II) in aqueous DMF containing ethylenediamine proceeds by way of the intermediate radicals which cyclize regioselectively in the n=4 and n=5 cases to give substituted methylenecycloalkanes.Experimental conditions which favor longer lifetimes for the intermediate radicals (low concentrations, slow addition times, and an inverse-addition mode) result in increased cyclization.The iodides curiously give more cyclic product than the corresponding bromides.These results are discussed.
- Crandall, Jack. K.,Michaely, W. J.
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p. 4244 - 4248
(2007/10/02)
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- Reactions with Phosphine Alkylenes, XLII. A Sequence for the Preparation of Acetylenes Starting from Carboxylic Chlorides and Phosphorus Ylides via 1,2-Diketones.
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Phosphorus ylides 1 and carboxylic chlorides 2 react with transylidation to give acyl ylides 3 which are oxidized with the adduct of ozone to triphenyl phosphite to yield 1,2-diketones 5.These are converted into the bis(hydrazones) 6 which are oxidized with O2/CuCl in pyridine giving acetylenes 7.
- Bestmann, Hans Juergen,Kumar, Kamlesh,Kisielowski, Lothar
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p. 2378 - 2382
(2007/10/02)
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- Poly(ethylene glycols) and Poly(ethylene glycol)-Grafted Copolymers Are Extraordinary Catalysts for Dehydrohalogenation under Two-Phase and Three-Phase Conditions
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Poly(ethylene glycols) 3> possess remarkably high activity as catalysts for dehydrohalogenation in organic-aqueous hydroxide two-phase systems, relative to classical phase-transfer agents, i. e., benzyltriethylammonium chloride and 18-crown-6.The importance of terminal hydroxyl groups together with the abrupt increase in catalyst activity and concentration in the organic layer on going from n=2 to n=3 and from n=3 to n=4 suggests the involvement of novel polymeric alkoxides I and/or hydroxides II.Moreover, the fact that maximum activity is obtained with n5 implies that an "18-crown-6-like" structure occuring at the terminus of the polymer chain is optimal for catalysis.Poly(ethylene glycols) grafted to cross-linked polystyrene display reasonably high activity.In preparative-scale conversions, such triphase catalysts can be recovered quantitatively by simple filtration and reused without significant loss in activity.
- Kimura, Yoshikazu,Regen, Steven L.
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p. 195 - 198
(2007/10/02)
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- Electrochemical Reduction of 1-Iodo-5-decyne and 1-Bromo-5-decyne at Mercury Cathodes in Dimethylformamide
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Pulse polarograms for 1-iodo-5-decyne in dimethylformamide containing tetramethylammonium perchlorate exhibit two waves.At potentials corresponding to the first wave, electrolysis of 1-iodo-5-decyne at mercury results in 5-decynyl radicals that (i) adsorb onto and interact with the mercury electrode to give 5-decynylmercury radicals which disproportionate into di-5-decynylmercury or (ii) cyclize and then accept a hydrogen atom to yield pentylidenecyclopentane.At potentials on the second wave, reduction of 1-iodo-5-decyne is largely a two-electron process leading to the 5-decynyl carbanion which is protonated by water in the solvent-supporting electrolyte to yield 5-decyne and hydroxide ion; hydroxide ion then attacks unreduced starting material to give 1-decen-5-yne and 5-decyn-1-ol.In the presence of excess proton donor (diethyl malonate), neither 1-decen-5-yne nor 5-decyn-1-ol is obtained, but diethyl 5-decynylmalonate is produced, the quantity of 5-decyne is increased, and the coulometric n value is raised.Pulse polarograms for 1-bromo-5-decyne show a single wave.For reduction of 1-bromo-5-decyne, the yields of 5-decyne and 1-decen-5-yne are comparable to those derived from 1-iodo-5-decyne; some di-5-decynylmercury is produced, but no pentylidenecyclopentane is formed.
- Shao, Rui-lian,Cleary, James A.,Perriere, Daniel M. La,Peters, Dennis G.
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p. 3289 - 3294
(2007/10/02)
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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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- Poly(ethylene glycols) Are Extraordinary Catalysts in Liquid-Liquid Two-Phase Dehydrohalogenation
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Poly(ethylene glycols) 3> are highly active and selective in catalyzing dehydrohalogenation in organic-aqueous hydroxide two-phase systems.
- Kimura, Yoshikazu,Regen, Steven L.
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p. 2493 - 2494
(2007/10/02)
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- Active Metals from Potassium-Graphite. Highly Dispersed Nickel on Graphite as a New Catalyst for the Stereospecific Semihydrogenation of Alkynes
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The reduction of NiBr2*2DME by means of potassium-graphite affords highly dispersed nickel on the graphite surface (Ni-Gr1).Freshly prepared Ni-Gr1 is used "in situ" as a catalyst for semihydrogenation of alkynes to alkenes in the presence of ethylenediamine as catalyst modifier.Unconjugated and conjugated (Z)-alkenes with a stereospecificity of 96-99percent and 94percent, respectively, are obtained.
- Savoia, Diego,Tagliavini, Emilio,Trombini, Claudio,Umani-Ronchi, Achille
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p. 5340 - 5343
(2007/10/02)
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- Chain-extension Reactions of Acetylenes. Part 4. Reaction of 1,3-Dilithioacetylides with Carbonyl Electrophiles, Hexamethylphosphoric Triamide, and Benzylideneaniline
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The regioselectivity of the reactions of 1,3-dilithioalk-1-ynes with various electrophiles has been examined.With formaldehyde and cyclic ketones, reaction occur at C-1 and C-3 to give alk-2-yne-1,5-diols.In contrast reactions with carbon dioxide give allene-1,3-dicarboxylic acids. 1,3-Dilithioalk-1-ynes decompose hexamethylphosphoric triamide and the resulting N-methylmethyleneamine undergoes addition only at the propargylic site.Further reaction with either 1-bromobutane or water gives alkynylamines.Benzylideneaniline also reacts with 1,3-dilithiohex- and hept-1-ynes only at the propargylic site to give N-phenylbut-3-ynylamines.
- Pover, Keith A.,Scheinmann, Feodor
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p. 2338 - 2345
(2007/10/02)
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