- Attractant pheromone for male rice bug, Leptocorisa chinensis: Semiochemicals produced by both male and female
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GC profiles of the airborne volatiles produced by adult males and females of the rice bug, L. chinensis showed no qualitative chemical dimorphism. However, GC-EAD experiments showed that eight of the compounds elicited strong responses in male and female antennae. Ruling out alarm pheromone and compounds that were not found in the whole-body extracts of the bugs, four compounds remained to be tested as possible attractants. In the field experiments, the whole mixture or tertiary blends were not attractive; however, males were strongly attracted to a 5:1 mixture of 2-(E)-octenyl acetate and octanol. The attractancy of the binary mixture was decreased by the addition of 3-(Z)-octenyl acetate. Although the binary lure specifically attracted males, there was no evidence that it triggered any response of sexual behavior in males.
- Leal, Walter Scares,Ueda, Yasuo,Ono, Mikio
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Read Online
- Regioselective Asymmetric Allylic Alkylation Reaction of α -Cyanoacetates Catalyzed by a Heterobimetallic Platina-/Palladacycle
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Allylic substitution reactions provide a valuable tool for the functionalization of CH acidic pronucleophiles. Often, control over the stereocenter generated at the nucleophilic reactant is still a challenge. The majority of studies that address this issue employ metal complexes with a low metal oxidation state (e.g. Pd0) to form allyl complexes through oxidative addition. In this article we describe the use of heterobimetallic PtII/PdII complexes, which probably activate the olefinic substrates through an SN2′ pathway. The reaction of α-cyanoacetates delivers linear allylation products with exclusive regioselectivity and high E/Z-selectivity for the new C=C double bond. Although the enantioselectivities attained are moderate, they are significantly higher than with related mono-PdII or -PtII catalysts or the corresponding bis-PdII complex, which indicates cooperation of the different metals. Control experiments suggest simultaneous activation of both reaction partners.
- Weiss, Marcel,Holz, Julia,Peters, Ren
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p. 210 - 227
(2016/01/20)
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- Ligand-controlled regiodivergent Ni-catalyzed reductive carboxylation of allyl esters with CO2
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A novel Ni-catalyzed regiodivergent reductive carboxylation of allyl esters with CO2 has been developed. This mild, user-friendly, and operationally simple method is characterized by an exquisite selectivity profile that is dictated by the ligand backbone.
- Moragas, Toni,Cornella, Josep,Martin, Ruben
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supporting information
p. 17702 - 17705
(2015/02/19)
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- Nickel-catalysed electrochemical carboxylation of allylic acetates and carbonates
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The electrochemical carboxylation of a series of allylic acetates and carbonates was carried out in the presence of CO2 under atmospheric pressure, with a catalytic amount of nickel-bipyridine complex, to afford the corresponding β,γ-unsaturated carboxylic acids. In the absence of nickel catalyst, alcohols were obtained.
- Medeiros,Pintaric,Olivero,Dunach
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experimental part
p. 4384 - 4389
(2011/06/22)
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- Acetoxyselenenylation of Olefins for the Preparation of Vinylic and Allylic Acetates
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Terminal and 1,2-disubstituted olefins were irreversibly acetoxyselenenylated by treatment with PhSeBr in an acetate buffer solution.Styrene derivatives yielded only Markovnikov adducts whereas simple terminal olefins and olefins containing an allylic oxygen substituent (acyloxy or aryloxy group) afforded significant amounts (50-85percent) of the anti-Markovnikov isomer.The product mixtures were isomerized to contain 90-97percent of the Markovnikov products by treatment with a catalytic amount (6-41percent) of BF3*OEt2 in chloroform.Oxidation (SO2Cl2/hydrolysis or MCPBA) of the isomerized products and selenoxide elimination at elevated temperature toward the acetoxy group afforded enol acetates in fair yields.The selenoxides of the anti-Markovnikov isomers (unisomerized mixtures) spontaneously eliminated, in the presence of the selenoxides of the Markovnikov isomer, to give allylic acetates in good yields at ambient temperature.
- Engman, Lars
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p. 884 - 890
(2007/10/02)
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- Stereoselective Preparation of (E)-Allyl Alcohols via Radical Elimination from anti-γ-Phenylthio-β-nitro Alcohols
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Phenylthio and hydroxymethyl groups may be introduced into nitroalkenes stereoselectively by treatment with benzenethiol and aqueous formaldehyde to give anti-γ-phenylthio-β-nitro alcohols, which are converted into (E)-allyl alcohols via radical elimination induced by Bu3SnH.
- Kamimura, Akio,Ono, Noboru
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p. 1278 - 1280
(2007/10/02)
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- The use of metal reagents in stereo- and regioselective functionalizations of conjugated dienes
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Conjugated dienes have been selectively functionalized via 1-acetoxy-4-chloro-2-alkenes and via 2-(phenylsulfonyl)-1,3-dienes.In both these approaches nucleophiles can be added to the 1- and 4-positions.It was shown that also non-stabilized carbon nucleophiles (from cuprates or copper(I)-catalyzed Grignard reactions) can be used.The utility of the functionalizations was demonstrated by the syntheses of a marine natural product and a butterfly pheromone.Finally, the 2-(phenyl-sulfonyl)-1,3-dienes show a dual electron demand in Diels-Alder reactions and give cycloadducts with both electron-rich and electron-deficient olefins.
- Baeckval, Jan-E
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p. 665 - 670
(2007/10/02)
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- Herstellung und Isomerisierung von 1-Alken-3-yl-acetaten und 2-Alken-1-yl-acetaten
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The allylic rearrangement of 1-alken-3-yl acetates in acetic acid containing sodium acetate proceeds at a slower rate but in higher yield than the rearrangement in the presence of strong proton acids.The predominant products are 2-alken-1-yl acetates. (E)-2-Hexen-1-yl acetate can be isomerized to the (Z)-isomer or rearranged to 1-hexen-3-yl acetate via the epoxide, depending upon the conditions of reduction of the epoxide.
- Garcia Martinez, Antonio,Oliver Ruiz, Manuel,Contelles, Jose Luis Marco
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p. 125 - 128
(2007/10/02)
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- METAL-CATALYZED REARRANGEMENTS OF ALLYLIC ESTERS
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It has been shown that Pd(CH3CN)2Cl2 catalyzes the rearrangement of allylic esters.Carbamates rearrange more rapidly than acetates which in turn rearrange more rapidly than carbonates.Allylic carbamates are more rapidly isomerized by Pd(CH3CN)2Cl2 than by Hg(OCOCF3)2.The rearrangement proceeds well except in cases where the central carbon of the allylic system is fully substituted.In contrast to the reported rearrangement of allylic carbamates by Hg2+ and previous reports of Pd2+-catalyzed rearrangements of allylic esters, this work showed the latter are extremely E specific; thus E allylic acetates yield equilibrium mixtures free of Z allylic isomers, under conditions in which Z allylic acetates are unreactive.This E specificity is applied to stereospecific 1,3-diene synthesis from bis E,Z-allylic acetates
- Oehlschlager, A. C.,Mishra, P.,Dhami, S.
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p. 791 - 797
(2007/10/02)
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- Syntheses of Acetates of 2(E)-Hexenol, 2(E)-Octenol and 2(E)-Decenol
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The sex attractants 2(E)-hexenol acetate (I), 2(E)-octenol acetate (II) and 2(E)-decenol acetate (III) have been synthesized.Selective C-alkylation of propargyl alcohol with n-propyl, n-pentyl and n-heptyl bromides furnishes the corresponding alkynes (IV, VI and VIII).Reduction of acetylenic bonds in IV, VI and VIII with LAH and subsequent acetylation afford the title compounds.
- Vig, O. P.,Jindal, R. T.
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p. 919 - 920
(2007/10/02)
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