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Cover Picture: Unusual Nitrile–Nitrile and Nitrile–Alkyne Coupling of FcCN and FcCCCN (Chem. Eur. J. 11/2014)
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Lisanne Becker Frank Strehler Marcus Korb Dr. Perdita Arndt Dr. Anke Spannenberg Dr. Wolfgang Baumann Prof. Dr. Heinrich Lang Prof. Dr. Uwe Rosenthal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(11):2969-2969
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2-Benzothiazole-carbaldehyde is transformed into di-O-acetyl-enol-(benzothiazolecarboxyl-2)-oin in the presence of acetic anhydride and of pyridine as catalyst. Without pyridine or with 2,6-lutidine no reaction occurs. A mechanism of this reaction is proposed. No reaction was observed in the case of benzaldehyde. Choral reacts with acetic anhydride in the presence of pyridine as well as of 2,6-lutidine as catalyst to give 1,1-diacetoxy-2,2,2-trichloro-ethane. A mechanism is proposed, in which in an intermediate state the acetate ion (and not pyridine, for steric reasons) attacks the carbon of the carbonyl function of the conjugate acid with the acetylium cation to yield 1,1-diacetoxy-2,2,2-trichloro-ethane. These two reactions occur only with aldehydes whose carbonyl is very electrophilic, and seem to be a possible way to point out the presence of an acylium cation in pyridine medium. 相似文献
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T. Hamaide N. Mariaggi J. L. Foureys P. Le Perchec A. Guyot 《Journal of polymer science. Part A, Polymer chemistry》1984,22(11):3091-3106
Polyoxyethylene macromers were used to prepare functionalized linear and crosslinked copolymers with styrene and divinylbenzene. Gel or macroporous resins were prepared. These copolymers and resins were used as anionic activators for the Williamson reaction of potassium phenoxide and alkyl bromides under solid–liquid or solid–liquid–liquid (triphase) conditions. In contrast to similar resins obtained from chemical grafting of polyoxyethylene onto chloromethylated styrene–divinylbenzene polymers, the activity factors were strongly dependent on the composition of the resins and their morphology: an optimum activity was obtained for a 0.05M fraction of macromers in soluble copolymers and crosslinked resins. In addition, a macroporous resin with large pores was more efficient than a gel-type resin of similar composition. These effects are discussed in terms of accessibility of the activating group and compatibility of the support with the medium. 相似文献
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Henri Magnin Firmin Rodriguez Marc Abadie Franois Schu 《Journal of polymer science. Part A, Polymer chemistry》1977,15(4):897-900
A kinetic study, as a function of temperature, of ethylene oligomerization by the n-BuLi–TMEDA complex allowed us to evaluate the thermodynamic parameters (ΔS? < ?23.7 u.e.) and thus to support a transition state where the ethylene is coordinated to the lithium atom. 相似文献
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Jean-Marc Bourgeois 《Helvetica chimica acta》1974,57(8):2553-2557
Treatment of 3-C-cyano-1,2:5,6-di-O-isopropylidene-3-O-(toluene-p-sulfonyl)-α-D -allofurannose with AlLiH4 or RMgX yields spiro-aziridines with two identical substituents on C(3′) (? H, ? CH3, ? C2H5). Reactions of these products and their derivatives are briefly described. If the C(3′) substituents are protons, the aziridine ring is easily opened. In acidic media (HCl), an amino-sugar containing the branched chain ? CH2Cl is produced; with hydrogenation, a ? CH3 branched chain results. If the C(3′) substituents are methyl groups, the aziridine ring cannot be opened neither with HCl nor with hydrogen. The acetylated derivative of this latter compound rearranges to the corresponding allylamide with HCl. For both types of spiro-aziridine, the nitrous deamination leads to the corresponding alkene. 相似文献
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