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Prof. Dr. José Luis García Ruano Dr. José Alemán Leyre Marzo Dr. Cuauhtémoc Alvarado Dr. Mariola Tortosa Dr. Sergio Díaz‐Tendero Dr. Alberto Fraile 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(27):8414-8422
We describe the unexpected behavior of the arylsulfonylacetylenes, which suffer an “anti‐Michael” addition of organolithiums producing their alkynylation under very mild conditions. The broad scope, excellent yields, and simplicity of the experimental procedure are the main features of this methodology. A rational explanation of all these results can be achieved by theoretical calculations, which suggest that the association of the organolithiums to the electrophile is a previous step of their intramolecular attack and is responsible for the unexpected “anti‐Michael” reactions observed for substituted sulfonylacetylenes. 相似文献
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Cuauhtémoc Pozos vázquez Russell Tayouo Christine Joly‐Duhamel Bernard Boutevin 《Journal of polymer science. Part A, Polymer chemistry》2010,48(10):2123-2134
The synthesis and characterization of poly(dimethylsiloxanes) bearing maleimides end‐groups (PDMSM) were carried out through imidization of maleic anhydride with three poly(dimethylsiloxanes) diamines of different molecular weights. Self‐photopolymerization of PDMSM was studied by Real‐Time Fourier Transform infrared spectroscopy (RT‐FTIR) and was possible even without photoinitiator (Darocur 1173). The reaction was found to proceed within seconds upon exposure to ultraviolet (UV) radiation to generate highly crosslinked polymer networks. The results indicated that these polymerizations were less sensitive to oxygen inhibition than the radical processes carried out on conventional UV‐curable acrylate resins. The thermal and mechanical properties of these resulting materials were studied starting from PDMS precursors with different molecular weights. These materials exhibit a low glass transition temperature (100 °C) and a high degradation temperature (400 °C) depending on the density of crosslinking points. These PDMSM are suitable as hydrophobic additives in a coating formulation based on a UV cured polypropylene glycol bismaleimide. Only a very small amount of silicone additives (0.3 wt %) is needed to change the wettability on the surface of the films. The migration of the additive was clearly shown before irradiation by scanning electron microscopy EDX and surface energy measurements. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2123–2134, 2010 相似文献
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JL García Ruano L Marzo V Marcos C Alvarado J Alemán 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(32):9775-9779
Center of attention: A new approach for the synthesis of enantiomerically enriched allenes by isomerization of 2-p-tolylsulfinylphenyl propargylic derivatives is presented, which in turn are prepared by reaction of sulfinylated lithium benzylcarbanions with arylsulfonylacetylenes. The high control of stereoselectivity in both steps is exerted by the sulfinyl group. 相似文献
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Ruano JL Alemán J Marzo L Alvarado C Tortosa M Díaz-Tendero S Fraile A 《Angewandte Chemie (International ed. in English)》2012,51(11):2712-2716
Chameleon: a new strategy for the synthesis of a wide variety of alkynyl derivatives by the reaction of substituted arylsulfonylacetylenes with organolithium species is described. The high yields, the simplicity of the experimental procedure, the broad scope of this reaction, and the formation of C(sp)-C(sp2) bonds without using transition metals are the main features of this methodology. 相似文献
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Ruano JL Alvarado C Díaz-Tendero S Alemán J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(14):4030-4037
The use of β-ketosulfoxides as nucleophiles in reactions with α,β-unsaturated aldehydes catalyzed by proline derivatives allows complete control of configuration at the two chiral centers that are created during 1,4-addition reactions. The sulfinyl group can be used to create additional chiral centers in the resulting compounds and then removed while preserving the chirality of the carbon joined to the sulfur. The catalyst and the sulfinyl group are mainly responsible for the configurational control of the carbon atoms acting as electrophile and nucleophile, respectively, which allows the preparation of the four possible diastereoisomers in optically pure form. Theoretical calculations of the possible chiral nucleophilic species bearing diastereotopic faces allow us to postulate, for the first time, that enolates, instead of enols, are the active reagents in these reactions. 相似文献
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S Velázquez-Olvera H Salgado-Zamora M Velázquez-Ponce E Campos-Aldrete A Reyes-Arellano C Pérez-Gonzalez 《Chemistry Central journal》2012,6(1):83
ABSTRACT: BACKGROUND: Imidazo[1,2-a]pyridines and pyrimidines are important organic fluorophores which have been investigated as biomarkers and photochemical sensors. The effect on the luminescent property by substituents in the heterocycle and phenyl rings, have been studied as well. In this investigation, series of 3-hydroxymethyl imidazo[1,2-a]pyridines and pyrimidines were synthesized and evaluated in relation to fluorescence emission, based upon the hypothesis that the hydroxymethyl group may act as an enhancer of fluorescence intensity. RESULTS: Compounds of both series emitted light in organic solvents dilutions as well as in acidic and alkaline media. Quantitative fluorescence spectroscopy determined that both fused heterocycles fluoresced more intensely than the parent unsubstituted imidazo[1,2-a]azine fluorophore. In particular, 3-hydroxymethyl imidazo[1,2-a]pyridines fluoresced more intensely than 3-hydroxymethyl imidazo[1,2-a]pyrimidines, the latter emitting blue light at longer wavelengths, whereas the former emitted purple light. CONCLUSION: It was concluded that in most cases the hydroxymethyl moiety did act as an enhancer of the fluorescence intensity, however, a comparison made with the fluorescence emitted by 2-aryl imidazo[1,2-a]azines revealed that in some cases the hydroxymethyl substituent decreased the fluorescence intensity. 相似文献