- Palladium-Catalyzed Synthesis of Alkynes via a Tandem Decarboxylation/Elimination of (E)-Enol Triflates
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A mild catalytic synthesis of alkynes via a tandem Pd-catalyzed decarboxylation/elimination of enol triflates is described. Key attributes of the method include readily available starting materials, broad functional group tolerance, and the ability to access terminal, internal, and halogenated alkynes. The preliminary scope of the reaction is demonstrated on 25 different examples with yields ranging from 63% to 96%.
- Munteanu, Charissa,Frantz, Doug E.
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supporting information
p. 3937 - 3939
(2016/08/30)
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- Copper-catalyzed aerobic oxidative transformation of ketone- Derived N-tosyl hydrazones: An entry to alkynes
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A novel strategy involving Cu-catalyzed oxidative transformation of ketone-derived hydrazone moiety to various synthetic valuable internal alkynes and diynes has been developed. This method features inexpensive metal catalyst, green oxidant, good functional group tolerance, high regioselectivity and readily available starting materials. Oxidative deprotonation reactions were carried out to form internal alkynes and symmetrical diynes. Cross-coupling reactions of hydrazones with halides and terminal alkynes were performed to afford functionalized alkynes and unsymmetrical conjugated diynes. A mechanism proceeding through a Cu-carbene intermediate is proposed for the CC triple bond formation.
- Li, Xianwei,Liu, Xiaohang,Chen, Huoji,Wu, Wanqing,Qi, Chaorong,Jiang, Huanfeng
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p. 14485 - 14489
(2015/02/05)
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- [(RCN)2PdCl2]-catalyzed E/Z isomerization of alkenes: A non-hydride binuclear addition-elimination pathway
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A crepuscular catalyst: Alkene migration catalyzed by [(RCN) 2PdCl2] complexes proceeds through an in situ generated Pd-H species. Addition of a 1,5-diene inhibits migration and allows the slower background catalysis of E/Z interconversion to be studied. Experimental and computational results suggest this interconversion proceeds through a conformational equilibrium in dipalladacycles (see picture). Copyright
- Tan, Emily H. P.,Lloyd-Jones, Guy C.,Harvey, Jeremy N.,Lennox, Alastair J. J.,Mills, Benjamin M.
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supporting information; experimental part
p. 9602 - 9606
(2011/12/05)
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- Decarboxylative elimination of enol triflates as a general synthesis of acetylenes.
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The enol trifluoromethanesulfonates 4, 8, 12, 17 and 20 of tert-butyl beta-ketodiesters and beta-ketoesters can be hydrolysed to the corresponding carboxylic acids by dissolution in trifluoroacetic acid. The dicarboxylic acids undergo mild decarboxylative elimination to give the acetylenic acids 4 and 9 in aqueous sodium bicarbonate solution at room temperature. Similarly, the monocarboxylic acids give the terminal and mid-chain acetylenes 13, 18, 21, and 24 by refluxing in acetone with potassium carbonate. One of the substituents on the acetylenes can be methyl, primary alkyl, secondary alkyl or ethynyl, and the other can be a carboxylic acid, hydrogen or primary alkyl, but the enol trifluoromethanesulfonates could not be prepared when one of the substituents was tert-butyl, nor when both substituents on the precursor to the acetylene were secondary alkyl.
- Fleming, Ian,Ramarao, Chandrashekar
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p. 1504 - 1510
(2007/10/03)
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- Polylithiumorganic compounds -21. On the Deproptonation of 1- and 3-Phenylpropyne as well as Phenylallene with Butyllithium. A Reinvestigation: Three Different Monoanions but one and the same Dianion
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In contrast to the literature, with butyllithium only one and the same dianion - namely 7 - is formed starting with each of the three hydrocarbons 1, 4, and 6.On the other hand, upon working at low temperature in tetrahydrofuran as the solvent we were able to detect the three corresponding monoanions 9, 15, and 16, most interestingly 15 and 16 at temperatures higher then -40 deg C show rearrangement with 1,3-hydrogen shift.
- Maercker, Adalbert,Fischenich, Jakob
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p. 10209 - 10218
(2007/10/02)
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- The Reaction of tert-Butyldiphenylsilylcuprates with Allenes
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Bis(tert-butyldiphenylsilyl)cuprate 1 reacts with allenes to form allyl- and vinyl-silanes.With allene itself the cuprate reagent shows a different regiochemistry from that of bis(phenyldimethylsilyl)cuprate.The regiochemistry can be controlled by choosing an appropriate reaction temperature.The intermediate cuprate 4 resulting from the addition of 1 to allene reacts with a wide variety of electrophiles giving functionalised allylsilanes.Phenylallenes isomerise to acetylenes.
- Barbero, Asuncion,Cuadrado, Purificacion,Gonzalez, Ana M.,Pulido, Francisco J.,Fleming, Ian
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p. 2811 - 2816
(2007/10/02)
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- A NEW PRACTICAL METHOD FOR THE SYNTHESIS OF ACETYLENES
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The reaction of isoxazol-5-ones derived from β-keto esters and hydroxylamine with sodium nitrite and ferrous sulphate in aqueous acetic acid affords the corresponding acetylenes in moderate to good yield. Key Words: Alkynes; Isoxazol-5-ones; β-Keto esters
- Boivin, Jean,Elkaim, Laurent,Ferro, Paul G.,Zard, Samir Z.
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p. 5321 - 5324
(2007/10/02)
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- Mechanism of the Nitrous Acid-Induced Dealkylation of Trisubstituted (Terminal Isopropylidene) Olefins to Form Acetylenes
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Evidence is presented that the conversion of olefins of type RCH=C(CH3)2 to acetylenes of structure RCCCH3 by the action of sodium nitrite in aqueous acetic acid proceeds by a sequence involving two nitrations, Nef conversion of one nitro group to carb
- Corey, E. J.,Seibel, William L.,Kappos, John C.
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p. 4921 - 4924
(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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