- Asymmetric Allylic Alkylation of Alkanoic-Acid Ester Enolates
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A protocol for the direct palladium-catalyzed asymmetric allylic alkylation of simple alkanoic-acid esters through their lithium enolates has been developed. The method permits to create stereogenic centers in the homo-allylic or allylic position. The configuration of the allylation products has been elucidated.
- Visse, Robin,M?llemann, Martin-Alexander,Braun, Manfred
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- Identification of a valuable kinetic process in copper-catalyzed asymmetric allylic alkylation
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Copper bottomed: The application of a previously described process of dynamic kinetic asymmetric transformation to acyclic substrates allowed the identification of a relevant kinetic process in the title reaction (see scheme; CuTC= copper(I) thiophencarboxylate, Naphth= naphthyl). The optimization of the reaction conditions and generality of the method, as well as mechanistic considerations are disclosed.
- Langlois, Jean-Baptiste,Alexakis, Alexandre
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supporting information; experimental part
p. 1877 - 1881
(2011/04/16)
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- Iodoenolcyclization. III. A General Approach to Tetrasubstituted Furans from 2-Alkenyl-1,3-Dicarbonyl Compounds.
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2,3,4,5-tetrasubstituted furans were easily obtained from of 2-alkenyl-1,3-dicarbonyl compounds by an efficient three steps synthesis.
- Antonioletti, Roberto,Cecchini, Cristina,Ciani, Barbara,Magnanti, Stefano
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p. 9019 - 9022
(2007/10/02)
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- The Reaction between Acyl Halides and Alcohols: Alkyl Halide vs. Ester Formation
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In the reaction between an acyl halide and an alcohol the thermodynamically favoured products are the free carboxylic acid and the alkyl halide.The initial reaction is, generally, the formation of an ester and HHal.When the alcohol is very prone to yield an alkyl cation upon protonation by HHal, formed H2O exhibited a superior reactivity and competed successfully with the alcohol for the acyl halide making, therefore, ester formation practically confined to a triggering role.But, in those cases where the cation is less easily formed, ester formation was favoured and, consequently, became the necessary elementary step towards alkyl halide formation.Tis final product, on the other hand, might be extremely slow to form in an SN2 reaction between the protonated ester function and the halide ion.In these instances, therefore, as well as in the cases when a basic solvent competes for the proton of HHal, the ester is the final product.A notable exception of the situation above outlined, is given by α-hydroxy-α-phenylbenzeneacetic acid (2y), which appears to undergo direct chlorine-hydroxyl interchange through a quaternary intermediate (E), in the end collapsing to α-chloro-α-phenyl-benzeneacetic acid (4y).Different systems were compared using CH2Cl2 as a solvent under strictly similar conditions.Some 28 different substrates were tested for reaction with AcCl (1a), whereas the action of eight acyl halides (a) against (RS)-α-methylbenzenemethanol (2n) and α-phenylbenzenemethanol (2p), as well as the effect of five different solvents on the reaction between two alcohols (2p and 2-methyl-2-propanol, 2c) with 1a, were observed.
- Strazzolini, Paolo,Giumanini, Angelo G.,Verardo, Giancarlo
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p. 217 - 254
(2007/10/02)
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- CATALYTIC CHLORINATION OF PIPERYLENE IN THE LIQUID PHASE
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During the chlorination of piperylene (1,3-pentadiene) in 1,2-dichloroethane and carbon tetrachloride, catalyzed by quaternary ammonium and phosphonium salts, the yield of substitutive chlorination products is reduced, and the proportion of addition products is increased.
- Shavanov, S. S.,Tolstikov, G. A.,Miniakhmetov, I. A.,Lomakina, S. I.,Khalilov, L. M.
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p. 837 - 840
(2007/10/02)
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- ON THE STEREOSELECTIVITY OF REACTIONS BETWEEN Α-METHYLBUT-2-ENYLSTANNANES AND ALDEHYDES.
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α-Methylbut-2-enylstannanes (7) - (9) react stereoselectively on heating with aldehydes to form anti-5-hydroxy-4-methyl-Z-pent-2-enes (16) and (17).In the presence of BF3*Et2O, the major products are the corresponding syn-5-hydroxy-4-methyl-E-pent-2-enes
- Hull, Caroline,Mortlock, Simon V.,Thomas, Eric J.
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p. 1007 - 1016
(2007/10/02)
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- Lewis Acid Catalysed Addition Reactions of 1,3-Alkyl Substituted Allyl Chlorides with Alkenes
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The zinc chloride-ether catalysed reactions of 2-unsubstituted allyl chlorides (5) with alkenes (6) yield linear addition products (7) which may undergo two types of sequential reactions: Electrophilic additions to alkenes (allyl chloride induced polymeri
- Mayr, Herbert,Klein, Herbert,Kolberg, Gerlinde
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p. 2555 - 2579
(2007/10/02)
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