1,720,975 research outputs found
Intermolecular interactions in Poly(2,6-dimethyl-1,4-Phenylenoxide) /(Poly(Styrene) blends from the study of FT-IR spectra at various temperatures
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Analysis of pulmonary tissue from a natural mummy of the XIII century (Saint Zita, Lucca, Tuscany, Italy) by FT-IR microspectroscopy
No full textFTIR Microspecytroscopy and DSC analysis of blends of Poly(vinylidene fluoride) with Isotactic and Syndiotactic Poly(Methyl Methacrylate)
No full textANALYTICAL INFRARED SPECTRAL DIFFERENCES BETWEEN HUMAN NORMAL AND LEUKEMIC-CELLS (CLL) .1.
No full textStudies on the transition metal catalyzed synthesis of variously substituted (E)-3-[1-(aryl)methylidene]- and (E)-3-(1-alkylidene)-3H-furan-2-ones
No full text5-Aryl and 5-alkyl substituted (E)-3-[1-(aryl)methylidene]- and (E)-3-(1-alkylidene)-3H-furan-2-ones, (E)-9, have been selectively synthesized by cyclization of the corresponding (E)-2-(1-alkynyl)-3-aryl/alkylpropenoic acids, (E)-11, in the presence of AgNO(3) or Pd-catalysts such as trans-di(mu-acetato)bis[(di-o-tolylphosphino)benzyl] or that constituted of a mixture of Et(3)N and PdCl(2)(PhCN)(2) or PdCl(2)(CH(3)CN)(2). in a 3 : 1 molar ratio, respectively. A representative (E)-5-aryl-3-[1-(aryl)methylidene]-3H-furan-2-one, i.e. (E)-9i, has been also prepared by a tandem process involving a Pd(0)- and Cu(I)-catalyzed cross-coupling reaction between an 1-alkyne and a (Z)-3-aryl-2-bromopropenoic acid followed by a catalytic innamolecular oxypalladation of the resulting cross-coupled product. However, when this same approach was used to prepare an (E)-5-alkyl-3-[1-(aryl)methylidene]-3H-furan-2-one, i.e. (E)-9j, a mixture of (E)-9j and the corresponding (E)/(Z)-5-(1-alkylidene)-3-(aryl)methyl-5H-furan-2-one, i.e. (E)/(Z)-20, was obtained. Finally, in an attempt to prepare an (E)-4-alkyl-5-aryl-3-[1-(aryl)methylidene]-3H-furan-2-one, i.e. (E)-14a, by a tandem process involving the intramolecular oxypalladation of an (E)-enynoic acid, (E)-11, followed by a cross-coupling reaction of the resulting compound with an aryl iodide, a (Z)-5-(1-alkynyl)-4-aryl-3-arylmethyl-5H-furan-2-one, i.e. (Z)-22, has been stereoselectively obtained. (C) 1997 Elsevier Science Ltd. All rights reserved
Reazioni di cross-coupling mediate da palladio tra reagenti organozinco e vinil nonaflati derivanti da beta-chetoesteri, beta-dichetoni ed alfa-dichetoni
No full textSynthesis of vinyl nonaflates derived from beta-ketoesters, beta-diketones and alpha-diketones and their palladium-catalyzed cross-coupling reactions with organozinc halides
No full textCyclic and acyclic beta-ketoesters 4, a typical cyclic alpha-diketone 5 and a typical cyclic beta-diketone 6 were convened to the corresponding vinyl nonaflates of general formula 7, 8 and 9, respectively, by reaction with 1.2-1.5 equiv of NaH in DMF at 20-55 degrees C followed by treatment with 1.15-1.30 equiv of perfluoro-1-butanesulfonyl fluoride at 20 degrees C. These vinyl nonaflates, which were purified by MPLC on silica gel, proved to be excellent electrophiles in Pd-catalyzed cross-coupling reactions with aryl-, 1-alkynyl- and alkylzinc chlorides. A variety of cyclic and acyclic tetrasubstituted alpha,beta-unsaturated esters which included stereoisomerically pure compounds, a 2-substituted 3-aryl-2-cyclopentenone and naturally-occurring dihydrojasmone were cleanly synthesized by these smooth and selective cross-coupling reactions. (C) 1999 Elsevier Science Ltd. All rights reserved
Analysis of pulmonary tissue of natural mummy of XIII century (Saint Zita, Lucca-Tuscany) by means of FT-IR microspectroscopy
No full textFourier tranformed infrared microspectroscopy study of skin fragments of the mummy from Hauslabjoch/Val Senales" (Southern Tyrol, Italy)
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