The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Christian Pichot - One of the best experts on this subject based on the ideXlab platform.
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Kinetic study of the "living" cationic polymerization of a galactose carrying vinyl ether. MALDI-TOF MS analysis of the resulting glycopolymers
International Journal of Biological Macromolecules, 2002Co-Authors: Franck D'agosto, Marie-thérèse Charreyre, Frédéric Delolme, Guy Dessalces, Henri Cramail, A. Deffieux, Christian PichotAbstract:The "living" cationic polymerization of a new saccharidic monomer, namely 1,2:3,4-di-O-isopropylidene-6-O-(2-vinyloxyethyl)-D-galactopyranose (GVE) has been investigated using acetaldehyde diethyl acetal/Trimethylsilyl Iodide as the initiating system in the presence of ZnCl2 as co-initiator. To determine if the process is living, the conversion was followed by dilatometry or by regularly withdrawing samples and analyzing them by H-1 NMR. Fast polymerization occurred together with a nonlinear ln([M](0)/[M](t)) = f(t) plot indicating an apparent loss of active centers. Nevertheless, the H-1 NMR- and SEC-determined molecular weights proved the absence of termination and transfer reactions during the polymerization process. MALDI-TOF mass spectrometry confirmed the absence of such side reactions and indicated a parallel initiation consecutive to the presence of water traces in the Trimethylsilyl. Iodide solution. The nonlinear ln([M](0)/[M](t)) = f(t) plot was attributed to specific interactions between the saccharidic rings and ZnCl2 and/or the growing carbocations.
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Kinetic Study of the “Living” Cationic Polymerization of a Galactose Carrying Vinyl Ether. MALDI-TOF MS Analysis of the Resulting Glycopolymers
Macromolecules, 2002Co-Authors: Franck D'agosto, Marie-thérèse Charreyre, Frédéric Delolme, Guy Dessalces, Henri Cramail, A. Deffieux, Christian PichotAbstract:The “living” cationic polymerization of a new saccharidic monomer, namely 1,2:3,4-di-O-isopropylidene-6-O-(2-vinyloxyethyl)-d-galactopyranose (GVE) has been investigated using acetaldehyde diethyl acetal/Trimethylsilyl Iodide as the initiating system in the presence of ZnCl2 as co-initiator. To determine if the process is living, the conversion was followed by dilatometry or by regularly withdrawing samples and analyzing them by 1H NMR. Fast polymerization occurred together with a nonlinear ln([M]0/[M] t) = f (t) plot indicating an apparent loss of active centers. Nevertheless, the 1H NMR- and SEC-determined molecular weights proved the absence of termination and transfer reactions during the polymerization process. MALDI−TOF mass spectrometry confirmed the absence of such side reactions and indicated a parallel initiation consecutive to the presence of water traces in the Trimethylsilyl Iodide solution. The nonlinear ln([M]0/[M] t) = f (t) plot was attributed to specific interactions between the sacchari...
Franck D'agosto - One of the best experts on this subject based on the ideXlab platform.
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Kinetic study of the "living" cationic polymerization of a galactose carrying vinyl ether. MALDI-TOF MS analysis of the resulting glycopolymers
International Journal of Biological Macromolecules, 2002Co-Authors: Franck D'agosto, Marie-thérèse Charreyre, Frédéric Delolme, Guy Dessalces, Henri Cramail, A. Deffieux, Christian PichotAbstract:The "living" cationic polymerization of a new saccharidic monomer, namely 1,2:3,4-di-O-isopropylidene-6-O-(2-vinyloxyethyl)-D-galactopyranose (GVE) has been investigated using acetaldehyde diethyl acetal/Trimethylsilyl Iodide as the initiating system in the presence of ZnCl2 as co-initiator. To determine if the process is living, the conversion was followed by dilatometry or by regularly withdrawing samples and analyzing them by H-1 NMR. Fast polymerization occurred together with a nonlinear ln([M](0)/[M](t)) = f(t) plot indicating an apparent loss of active centers. Nevertheless, the H-1 NMR- and SEC-determined molecular weights proved the absence of termination and transfer reactions during the polymerization process. MALDI-TOF mass spectrometry confirmed the absence of such side reactions and indicated a parallel initiation consecutive to the presence of water traces in the Trimethylsilyl. Iodide solution. The nonlinear ln([M](0)/[M](t)) = f(t) plot was attributed to specific interactions between the saccharidic rings and ZnCl2 and/or the growing carbocations.
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Kinetic Study of the “Living” Cationic Polymerization of a Galactose Carrying Vinyl Ether. MALDI-TOF MS Analysis of the Resulting Glycopolymers
Macromolecules, 2002Co-Authors: Franck D'agosto, Marie-thérèse Charreyre, Frédéric Delolme, Guy Dessalces, Henri Cramail, A. Deffieux, Christian PichotAbstract:The “living” cationic polymerization of a new saccharidic monomer, namely 1,2:3,4-di-O-isopropylidene-6-O-(2-vinyloxyethyl)-d-galactopyranose (GVE) has been investigated using acetaldehyde diethyl acetal/Trimethylsilyl Iodide as the initiating system in the presence of ZnCl2 as co-initiator. To determine if the process is living, the conversion was followed by dilatometry or by regularly withdrawing samples and analyzing them by 1H NMR. Fast polymerization occurred together with a nonlinear ln([M]0/[M] t) = f (t) plot indicating an apparent loss of active centers. Nevertheless, the 1H NMR- and SEC-determined molecular weights proved the absence of termination and transfer reactions during the polymerization process. MALDI−TOF mass spectrometry confirmed the absence of such side reactions and indicated a parallel initiation consecutive to the presence of water traces in the Trimethylsilyl Iodide solution. The nonlinear ln([M]0/[M] t) = f (t) plot was attributed to specific interactions between the sacchari...
Farhad Panahi - One of the best experts on this subject based on the ideXlab platform.
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Trimethylsilyl Iodide as a multifunctional agent in the one pot synthesis of 9 1h indol 3 yl xanthen 4 9h ones from o methyl protected salicylaldehydes indoles and β dicarbonyl compounds
ChemInform, 2015Co-Authors: Ali Khalafinezhad, Maryam Nourisefat, Farhad PanahiAbstract:Trimethylsilyl Iodide is introduced as an efficient reagent for the one-pot synthesis of various xathenone derivatives.
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Trimethylsilyl Iodide as a Multifunctional Agent in the One-Pot Synthesis of 9-(1H-Indol-3-yl)xanthen-4-(9H)-ones from O-Methyl Protected Salicylaldehydes, Indoles, and β-Dicarbonyl Compounds
Synthesis, 2014Co-Authors: Ali Khalafi-nezhad, Maryam Nourisefat, Farhad PanahiAbstract:Trimethylsilyl Iodide (TMSI) is introduced as an efficient reagent for the one-pot synthesis of 9-(1H-indol-3-yl)xanthen-4-(9H)-ones using the reaction of 2-methoxybenzaldehydes (as O-methyl protected salicylaldehydes), indoles, and β-dicarbonyl compounds. In this protocol, a set of TMSI reactions involving silylation, silyl enol ether formation, methyl deprotection, and nucleophilic substitution/cyclization are performed to furnish the target product. The key step in this protocol is the deprotection of the methoxy group by TMSI.
Paul L. Ornstein - One of the best experts on this subject based on the ideXlab platform.
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A new method for the efficient conversion of alcohols into Iodides via treatment with Trimethylsilyl Iodide
Tetrahedron Letters, 2001Co-Authors: Michael E. Jung, Paul L. OrnsteinAbstract:The conversion of alcohols into alkyl Iodides is very often a useful and necessary organic transformation. We wish now to report a simple and efficient one-step method for the conversion of alcohols into Iodides under mild conditions via treatment of the alcohols or their Trimethylsilyl ethers with the interesting electrophilic reagent, Trimethylsilyl Iodide.' The two classical methods for this reaction are a) the use of red phosphorus and molecular iodine,3 and b) the reaction of alcohols with hydrogen Iodide, usually generated in situ from alkali -Iodide and acid. 4 Several newer methods have appeared recently which utilize a variety of phosphorus and boron derivatives and in which formation of a molecule containing a very stable phosphorus-oxygen double bond (phosphonate5 and phosphate6 derivatives) or a boron-oxygen single bond7 provides a large part of the driving force for the reaction. Finally, conversion of the alcohol into a good leaving group followed by nucleophilic attack by Iodide ion forms the basis of several other recent techniques for this transformation.8
Tiziana Funaioli - One of the best experts on this subject based on the ideXlab platform.
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novel 1 4 5 8 phenanthrenediquinones and unusual deoxygenation with Trimethylsilyl Iodide
European Journal of Organic Chemistry, 2009Co-Authors: Karsten Krohn, Abdulselam Aslan, Ishtiaq Ahmed, Gennaro Pescitelli, Tiziana FunaioliAbstract:Attempt for aryl methyl ether cleavage of 5,8-dimethoxy-1,4-phenanthrenequinone (4) with boron trichloride or tribromide resulted in the halogenation of the quinone double bond to form 5a,b. Surprisingly, reaction of dimethyl ether 4 with Trimethylsilyl Iodide afforded the phenanthrenediquinone 6, whereas deoxygenation to 8 and 9 occurred by reaction of Trimethylsilyl Iodide with derivative 7. The phenanthrenediquinones 6 and 10 were obtained nearly quantitatively from 4 and 7 by using ceric ammonium nitrate as the oxidant. The cyclic voltammograms of the phenanthrenediquinones 6 and 10 were studied and rationalized by Huckel Molecular Orbital calculations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
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Novel 1,4,5,8‐Phenanthrenediquinones and Unusual Deoxygenation with Trimethylsilyl Iodide
European Journal of Organic Chemistry, 2009Co-Authors: Karsten Krohn, Abdulselam Aslan, Ishtiaq Ahmed, Gennaro Pescitelli, Tiziana FunaioliAbstract:Attempt for aryl methyl ether cleavage of 5,8-dimethoxy-1,4-phenanthrenequinone (4) with boron trichloride or tribromide resulted in the halogenation of the quinone double bond to form 5a,b. Surprisingly, reaction of dimethyl ether 4 with Trimethylsilyl Iodide afforded the phenanthrenediquinone 6, whereas deoxygenation to 8 and 9 occurred by reaction of Trimethylsilyl Iodide with derivative 7. The phenanthrenediquinones 6 and 10 were obtained nearly quantitatively from 4 and 7 by using ceric ammonium nitrate as the oxidant. The cyclic voltammograms of the phenanthrenediquinones 6 and 10 were studied and rationalized by Hückel Molecular Orbital calculations
