- Two-way homologation of aliphatic aldehydes: Both one-carbon shortening and lengthening via the same intermediate
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Aliphatic aldehydes can be homologated to both one-carbon shorter and one-carbon longer homologous carbonyl compounds through the 2–4 steps of reactions via the same intermediates, β,γ-unsaturated α-nitrosulfones, prepared from the proline-catalyzed sequential reactions of several aliphatic aldehydes with phenylsulfonylnitromethane. While the oxidative cleavage of the key intermediates gave one-carbon less homologous carbonyl compounds, the reduction of the same key intermediates followed by an oxidation produced one-carbon more homologous carbonyl compounds.
- Yoo, Jae Won,Seo, Youngran,Park, Jong Beom,Kim, Young Gyu
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- Regioselective hydromethoxycarbonylation of terminal alkynes catalyzed by palladium(II)-tetraphos complexes
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An in situ generated dinuclear palladium hydride complex bearing cis,trans,cis-1,2,3,4-tetrakis(diphenylphosphanyl)cyclobutane catalyzed the hydromethoxycarbonylation of terminal alkynes, giving the corresponding branched α,β-unsaturated ester (A) with high regioselectivity.
- Oberhauser, Werner,Ienco, Andrea,Vizza, Francesco,Trettenbrein, Barbara,Oberhuber, Dennis,Strabler, Christof,Ortner, Teresa,Brueggeller, Peter
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experimental part
p. 4832 - 4837
(2012/10/08)
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- Teflon AF-2400 mediated gas-liquid contact in continuous flow methoxycarbonylations and in-line FTIR measurement of CO concentration
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We report on the development of a continuous flow process for the palladium catalysed methoxycarbonylation of aryl, heteroaromatic and vinyl iodides and an aryl bromide using a Teflon AF-2400 based Tube-in-Tube reactor to mediate the selective permeation of carbon monoxide into solution at elevated pressures. The low volume of pressurised gas within the reactor (5.6 mL) offers the potential for an enhanced safety profile compared to batch processes. We also present preliminary results for the use of in situ FTIR to measure solution concentrations of carbon monoxide and demonstrate the use of a second reactor to effect the removal of carbon monoxide from the flow stream.
- Koos, Peter,Gross, Ulrike,Polyzos, Anastasios,O'Brien, Matthew,Baxendale, Ian,Ley, Steven V.
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supporting information; experimental part
p. 6903 - 6908
(2011/10/31)
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- Synthesis of α,α′-disubstituted linear ethers by an intermolecular nicholas reaction - Application to the synthesis of (+)-cis/-trans-lauthisan and (+)-cis/(+)-trans-obtusan
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A new and efficient methodology to prepare α,α'-disubstituted linear ethers through an intermolecular Nicholas reaction (interNR) is described. cis-2,8-Disubstituted oxocanes, cis-2,9-disubstituted oxonanes, their trans isomers, and their parent unsaturat
- Ortega, Nuria,Martin, Tomas,Martin, Victor S.
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scheme or table
p. 554 - 563
(2009/09/06)
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- Chemoselective cross-metathesis reaction between electron-deficient 1,3-dienes and olefins
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Chemoselective cross-metathesis reactions between methyl sorbate or 1,3-dienic amides and various olefins in the presence of the Grubbs-Hoveyda catalyst have been investigated. Cross-metathesis reactions turned out to be more chemoselective with 1,3-dienic amides than with 1,3-dienic esters.
- Ferrie, Laurent,Amans, Dominique,Reymond, Sebastien,Bellosta, Veronique,Capdevielle, Patrice,Cossy, Janine
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p. 5456 - 5465
(2007/10/03)
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- Zinc metal-promoted stereoselective olefination of aldehydes and ketones with gem-dichloro compounds in the presence of chlorotrimethylsilane
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A combination of zinc metal and a catalytic amount of chlorotrimethylsilane has been found to promote the transformation of various aldehydes and ketones with gem-dichloro compounds, such as benzylidene dichloride (1a) and methyl dichloroacetate (1b), to the corresponding cross- coupling products, such as substituted styrene 3 and methyl acrylates 4 derivatives, under mild reaction conditions in THF. The E-isomer of the corresponding alkenes was obtained stereoselectively in good-to-excellent yields. The reaction serves as a very convenient one-pot procedure.
- Ishino, Yoshio,Mihara, Masatoshi,Nishihama, Shintaro,Nishiguchi, Ikuzou
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p. 2669 - 2672
(2007/10/03)
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- Synthesis of α,β-unsaturated aldehydes and methyl carboxylic esters from 2-acetylenic phenyl sulfides
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2-Alkynylthio benzenes were reduced to 2-Alkenylthio benzenes with diisobutyl aluminum hydride. Mono chlorination of these compounds with sulfuryl chloride and pyridine followed by hydrolysis, in the presence of Cu(II) salts, gave α,β-unsaturated aldehydes. 2-Alkynylthio benzenes were converted into 2-Alkynyl 1,1-bis thiobenzenes by monochlorination with sulfuryl chloride and pyridine followed by treatment with thiophenol and triethylamine. These substances were then converted to α,β-unsaturated methyl carboxylic esters by way of isomerization with sodium methoxide to the corresponding allene and treatment with hydrochloric acid and methanolysis in the presence of iodine.
- Fortes, Carlos C.,Garrote, Clevia F. D.
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p. 3917 - 3941
(2007/10/03)
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- From Stoichiometry to Catalysis: Electroreductive Coupling of Alkynes and Carbon Dioxide with Nickel-Bipyridine Complexes. Magnesium Ions as the Key for Catalysis
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The incorporation of carbon dioxide into nonactivated alkynes catalyzed by electrogenerated nickel-bipyridine complexes affords α,β-unsaturated acids in moderate to good yields.The electrocarboxylation reaction was undertaken on a preparative scale in the presence of a sacrificial magnesium anode: the formation of acids from alkynes is stoichiometric with respect to the nickel complex if performed in a two-compartment cell but can be made catalytic in a single-compartment cell.An intermediate nickelacycle was isolated from the reaction with 4-octyne.The cleavage ofthis metallacycle by magnesium ions is the key step to explain catalysis.
- Derien, Sylvie,Dunach, Elisabet,Perichon, Jacques
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p. 8447 - 8454
(2007/10/02)
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- NOVEL SELECTIVE SYNTHESIS OF α-CHLOROMETHYL, α,α-DICHLOROMETHYL, AND α,α,α-TRICHLOROMETHYL KETONES FROM ALDEHYDE UTILIZING ELECTROREDUCTION AS KEY REACTIONS
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A variety of α-chloromethyl, α,α-dichloromethyl, and α,α,α-trichloromethyl ketones were synthesized from aldehyde utilizing cathodic reduction as key reactions.
- Shono, Tatsuya,Kise, Naoki,Yamazaki, Akira,Ohmizu, Hiroshi
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p. 1609 - 1612
(2007/10/02)
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