Search

Your search keyword '"Parella, Teodor"' showing total 1,197 results
Start Over Author "Parella, Teodor"
1,197 results on '"Parella, Teodor"'

208. ChemInform Abstract: Sequential Biocatalytic Aldol Reactions in Multistep Asymmetric Synthesis: Pipecolic Acid, Piperidine and Pyrrolidine (Homo)Iminocyclitol Derivatives from Achiral Building Blocks.

Author

Soler, Anna, primary, Garrabou, Xavier, additional, Hernandez, Karel, additional, Gutierrez, Mariana L., additional, Busto, Eduardo, additional, Bujons, Jordi, additional, Parella, Teodor, additional, Joglar, Jesus, additional, and Clapes, Pere, additional

Published
2015
Full Text
View/download PDF

212. Can the disproportion of oxidation state III be favored in Ru(super II)-OH(sub 2)/Ru(super IV)=O systems?

Author

Masllorens, Ester, Rodriguez, Montserrat, Romero, Isabel, Roglans, Anna, Parella, Teodor, Benet-Buchholz, Jordi, Poyatos, Macarena, and Llobet, Antoni

Subjects
Oxidation-reduction reaction -- Analysis, Ruthenium -- Chemical properties, Isomerization -- Analysis, Pyridine -- Chemical properties, Styrene -- Chemical properties, Chemistry
Abstract

Reaction mechanisms for the oxidations of several substrates by Ru(super IV) = O was established and catalytic oxidations systems were described to get an insight into the rich oxidative properties of the Ru(super IV) = O species. The results show inverse correlation between the ratio of cis/trans epoxide isomerization in the catalytic oxidation of cis-beta-methylstyrene and (DELTA)E(sub 1/2) and only traces of the trans epoxide were formed when using cis-2 and trans-2 complexes as catalysts, demonstrating that the process was highly stereoselective.

Published
2006

213. Biocatalytic asymmetric self- and cross-aldol reaction of glycolaldehyde. A new activity of D-fructose-6-phosphate aldolase

Author

Garrabou, Xavier, Castillo, José A., Hélaine, Christine, Parella, Teodor, Joglar, Jesus, Lemaire, Marielle, Clapés, Pere, Synthèse et étude de systèmes à intêret biologique (SEESIB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), SERVEI DE RMN, Universitat Autònoma de Barcelona (UAB), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
aldol reaction • aldolases • aldoses • enzyme catalysis • glycolaldehydes, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2009
Full Text
View/download PDF

214. pH-induced luminescence changes of chromophore-quencher tricarbonylpolypyridylrhenium(I) complexes with 4-pyridinealdazine

Author

Cattaneo, Mauricio, Fagalde, Florencia, Katz, Néstor Eduardo, Borsarelli, Claudio Darío, and Parella, Teodor

Subjects
mixed valent compound, photochemistry, molecular devices, Físico-Química, Ciencia de los Polímeros, Electroquímica, Ciencias Químicas, rhenium, Donor-accepto systems, CIENCIAS NATURALES Y EXACTAS
Abstract

New chromophore-quencher rhenium(I) tricarbonyls, of formulae [Re(4,4’-X2-bpy)(CO)3(PCA)]+, [(4,4’-X2-bpy)(CO)3Re(μ-PCA)Re(CO)3(4,4’-X2-bpy)]2+, and [(4,4’-X2-bpy)(CO)3ReI-(μ-PCA)-RuII(NH3)5]3+, with X = Ph or CO2Me and PCA = 4-pyridinealdazine, have been synthesized as PF6- salts andcharacterized by spectroscopic, electrochemical and photophysical techniques. Contrasting to previously reported species with X = Me or H, these complexes emit at room temperature in CH3CN. The recovery of luminescence can thus be ascribed to the change of energy levels induced by adding electron-withdrawing substituents to the 2,2´-bipyridine ring, since the emissive ReII(X2bpy-) excited state becomes much lower in energy than ReII(PCA-) non-emissive excited state. For the mononuclear and the symmetric dinuclear rhenium(I) complexes with X = CO2Me in aqueous solutions, consecutive protonation of both pyridinic and imine N atoms of PCA cause unusual bell-shaped curves of both the absorption and the emission intensities vs. pH, because of opposite effects on the electronic delocalization of PCA. Therefore, the latter property can be employed to devise novel luminescent sensors of acidity of the on-off-on type. The corresponding unsymmetric dinuclear complexes, of formula [(4,4’-X2-bpy)(CO)3ReI(μ- PCA)RuIII(NH3)5]4+, were obtained in situ by oxidizing the [ReI,RuII] precursors in CH3CN solution; from spectral and electrochemical measurements, the values of the metal-to-metal electronic coupling elements have been determined. Fil: Cattaneo, Mauricio. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Fagalde, Florencia. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Katz, Néstor Eduardo. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Borsarelli, Claudio Darío. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias. Instituto de Ciencias Químicas; Argentina. Universidad Nacional de Santiago del Estero. Instituto de Bionanotecnología del Noa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Bionanotecnología del Noa; Argentina Fil: Parella, Teodor. Servei de Rmn; España

Published
2007
Full Text
View/download PDF

215. Synthesis, structure, redox properties, and catalytic activity of new ruthenium complexes containing neutral or anionic and facial or meridional ligands : an evaluation of electronic and geometrical effects

Author

Gomez, Montserrat, Sala, Xavier, Plantalech, Elena, Rodriguez, Montserrat, Romero, Isabel, Jansat, Susanna, Parella, Teodor, Stoeckli-Evans, Helen, Solans, Xavier, Font-Bardia, Merce, Vidjayacoumar, Balamurugan, Llobet, Antoni, Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Departament de Quimica, Universitat de Girona, Universitat de Girona (UdG), Laboratoire de chimie de coordination (LCC), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), SERVEI DE RMN, Universitat Autònoma de Barcelona (UAB), INSTITUTE OF CHEMISTRY, Université de Neuchâtel (UNINE), and Institute of Chemical Research of Catalonia (ICIQ)

Subjects
[CHIM.ORGA]Chemical Sciences/Organic chemistry, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2007

216. Accurate measurement of JHH in overlapped signals by a TOCSY-edited SERF Experiment.

Author

Fredi, André, Nolis, Pau, and Parella, Teodor

Subjects
PROTON-proton interactions, COUPLING constants, NUCLEAR excitation, SIGNAL frequency estimation, PROTON synchrotrons
Abstract

Selective refocusing (GSERF or the recent PSYCHEDELIC) experiments were originally designed to determine all proton-proton coupling constants ( JHH) for a selected proton resonance. They work for isolated signals on which selective excitation can be successfully applied but, as it happens in other selective experiments, fail for overlapped signals. To circumvent this limitation, a doubly-selective TOCSY-GSERF scheme is presented for the measurement of JHH in protons resonating in crowded regions. This new experiment takes advantage of the editing features of an initial TOCSY transfer to uncover hidden resonances that become accessible to perform the subsequent frequency-selective refocusing. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

217. Structural discrimination from in situ measurement of 1 DCH and 2 DHH residual dipolar coupling constants.

Author

Marcó, Núria, Gil, Roberto R., and Parella, Teodor

Subjects
ZWITTERIONS, COUPLING constants, NUCLEAR magnetic resonance spectroscopy, RESIDUAL stresses, STEREOISOMERISM
Abstract

A fast residual dipolar coupling constant-assisted strategy involving the simultaneous determination of scalar and total coupling constants from a single 1 JCH/2 JHH-resolved NMR spectrum is reported. It is shown that the concerted use of the directly measured 1 DCH (for all CHn multiplicities) and 2 DHH residual dipolar couplings allows an on-the-fly assignment of diastereotopic CH2 protons, as well as of an efficient discrimination between diastereoisomeric structures of strychnine which contains six stereocenters. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

218. Improving the performance of J-modulated ADEQUATE experiments through homonuclear decoupling and non-uniform sampling.

Author

Saurí, Josep, Parella, Teodor, Williamson, R. Thomas, and Martin, Gary E.

Subjects
*NUCLEAR magnetic resonance, *IRREGULAR sampling (Signal processing), *MATHEMATICAL decoupling, *SPECTRUM analysis, *MEASUREMENT
Abstract

Homonuclear 13C-13C couplings at natural abundance can be measured using the J-modulated Adequate DoublE QUAntumTransfer Experiment (ADEQUATE) experiment. To somewhat ameliorate F1 digitization requirements, a scaling factor was incorporated into the original pulse sequence. Non-uniform sampling provides an obvious avenue to further facilitate the acquisition of 1 JCC and n JCC homonuclear coupling constant data. We introduce homonuclear decoupling (HD) analogous to that described for the 1,1-HD-ADEQUATE and 1,n-HD-ADEQUATE experiments and evaluate the combination of non-uniform sampling and HD on the acquisition of both 1 JCC and n JCC homonuclear 13C-13C coupling constants using ibuprofen as a model compound. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

220. Chiral Induction in Intramolecular Rhodium-Catalyzed [2+2+2] Cycloadditions of Optically Active Allene-ene/yne-allene Substrates.

Author

Haraburda, Ewelina, Fernández, Martí, Gifreu, Anna, Garcia, Jordi, Parella, Teodor, Pla ‐ Quintana, Anna, and Roglans, Anna

Subjects
ASYMMETRIC synthesis, PLATINUM group, ALLENE synthesis, RING formation (Chemistry), RHODIUM catalysts
Abstract

Allene-yne-allene and allene-ene-allene N-tosyl-linked substrates with two chiral centres in the α-position of the allene moiety were satisfactorily prepared starting both from racemic and chiral propargylic alcohols. The Wilkinson's complex-catalyzed [2+2+2] cycloaddition reaction of these substrates was evaluated. In the case of enantiomerically pure bisallenes, high stereoselectivity was observed, giving a diastereomerically pure cycloadduct. The chirality of starting bisallene substrates can be completely transferred to the cycloadducts, representing an atom-economical and enantiospecific process for the construction of fused polycycles. However, when reacting an oxygen-linked allene-ene-allene substrate, the stereoselectivity decreased and two diastereoisomers were formed. A detailed characterization study of the resulting cycloadducts allowed us to identify the enantioisomer generated in the cycloaddition. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

226. Hydrosilylation of internal alkynes catalyzed by tris-imidazolium salt-stabilized palladium nanoparticles

Author

Universidad de Alicante. Departamento de Química Orgánica, Universidad de Alicante. Instituto Universitario de Síntesis Orgánica, Planellas, Marc, Guo, Wusheng, Alonso Valdés, Francisco, Yus Astiz, Miguel, Shafir, Alexandr, Pleixats, Roser, Parella, Teodor, Universidad de Alicante. Departamento de Química Orgánica, Universidad de Alicante. Instituto Universitario de Síntesis Orgánica, Planellas, Marc, Guo, Wusheng, Alonso Valdés, Francisco, Yus Astiz, Miguel, Shafir, Alexandr, Pleixats, Roser, and Parella, Teodor

Abstract

Palladium nanoparticles stabilized with tris-imidazolium tetrafluoroborates catalyze the stereoselective hydrosilylation of internal alkynes in a dry inert atmosphere to give (E)-vinylsilanes in excellent yields. In the presence of controlled amounts of water a transfer hydrogenation reaction takes place with the formation of (Z)-alkenes or the corresponding alkanes.

Published
2014

227. Observació directa de cicles redox de Ag(I)/Ag(III) de dos electrons en catàlisi de funcionalització d’halurs d’aril

Author

Font, Marc, Acuña-Parés, Ferran, Parella, Teodor, Serra, Jordi, M. Luis, Josep, Lloret-Fillol, Julio, Costas, Miquel, Ribas, Xavi, Font, Marc, Acuña-Parés, Ferran, Parella, Teodor, Serra, Jordi, M. Luis, Josep, Lloret-Fillol, Julio, Costas, Miquel, and Ribas, Xavi

Abstract

La plata és avui dia àmpliament utilitzada en catàlisi homogènia per a la síntesi de compostos orgànics a causa del seu caràcter d’àcid de Lewis i el seu poder oxidant. La Ag(I) és un potent oxidant monoelectrònic que troba utilitat en un gran nombre de processos catalítics. Tanmateix, els cicles catalítics de dos electrons, molt comuns en la química organometàl·lica dels metalls nobles, no han estat mai considerats possibles per a la plata. En aquest estudi descrivim un cicle catalític Ag(I)/Ag(III) que és operatiu en una reacció model d’acoblament creuat per a la formació d’enllaços C–O. Espècies aril–Ag(III) han estat inequívocament identificades com a intermedis d’aquest cicle catalític. L’estudi de la síntesi i la reactivitat de l’esmentat complex ha permès per primera vegada la caracterització de les etapes d’addició oxidant i eliminació reductiva de formació d’enllaços carboni–nucleò-fil en centres monometàl·lics de plata. El present treball demostra que els processos d’eliminació reductiva en espècies aril–Ag(III) són efectius en reaccions d’acoblament creuat per a la formació d’enllaços C–O, C–N, C–S, C–C i C–halur, incloses les reaccions de fluoració d’arils. Aquest estudi suposa un punt de partida per a l’expansió de la química redox Ag(I)/Ag(III) a noves metodologies per a la síntesi orgànica, en analogia a la química d’acoblament creuat del coure o el pal·ladi. A més, els resultats descrits proporcionen una comprensió mecanística fonamental única en les reaccions d’acoblament, Silver is extensively used in homogeneous catalysis for organic synthesis owing to its Lewis acidity and unique high oxidation power. The high oxidation potential of Ag(I) makes it a powerful one-electron oxidant that finds utility in a large number catalytic processes. However, two-electron redox catalytic cycles, most common in noble metal organometallic reactivity, have never been considered. Herein we show that an Ag(I)/Ag(III) catalytic cycle is operative in a model C–O cross-coupling reaction. Aryl–Ag(III) species have been unequivocally identified as an intermediate in the catalytic cycle. The study of the synthesis and reactivity of this complex has enabled for the first time the direct characterization of aryl halide oxidative addition and carbon–nucleophile bond-forming reductive elimination steps at monometallic silver centers. This report demonstrates that reductive elimination processes at aryl–Ag(III) species are effective for C–O, C–N, C–S, C–C and C–halide coupling reactions, including aryl fluorination. We anticipate our study as the starting point for expanding Ag(I)/Ag(III) redox chemistry into new methodologies for organic synthesis, resembling well-known copper or palladium cross-coupling catalysis. Furthermore, findings described herein provide a unique fundamental mechanistic understanding of Ag-catalyzed cross-coupling reactions and dismiss the generally accepted conception that silver redox chemistry can only arise from one-electron processes.Keywords: Cross-coupling, high oxidation states, redox chemistry, reaction mechanisms, silver.

Published
2014

228. Sponge-like molecular cage for purification of fullerenes

Author

European Research Council, Ministerio de Ciencia e Innovación (España), Generalitat de Catalunya, European Commission, García-Simón, Cristina, Gómez, Laura, Parella, Teodor, Imaz, Inhar, Maspoch, Daniel, Costas, Miquel, Ribas, Xavi, European Research Council, Ministerio de Ciencia e Innovación (España), Generalitat de Catalunya, European Commission, García-Simón, Cristina, Gómez, Laura, Parella, Teodor, Imaz, Inhar, Maspoch, Daniel, Costas, Miquel, and Ribas, Xavi

Abstract

Since fullerenes are available in macroscopic quantities from fullerene soot, large efforts have been geared toward designing efficient strategies to obtain highly pure fullerenes, which can be subsequently applied in multiple research fields. Here we present a supramolecular nanocage synthesized by metal-directed self-assembly, which encapsulates fullerenes of different sizes. Direct experimental evidence is provided for the 1:1 encapsulation of C60, C70, C76, C78 and C84, and solid state structures for the host–guest adducts with C60 and C70 have been obtained using X-ray synchrotron radiation. Furthermore, we design a washingbased strategy to exclusively extract pure C60 from a solid sample of cage charged with a mixture of fullerenes. These results showcase an attractive methodology to selectively extract C60 from fullerene mixtures, providing a platform to design tuned cages for selective extraction of higher fullerenes. The solid-phase fullerene encapsulation and liberation represent a twist in host–guest chemistry for molecular nanocage structures.

Published
2014

229. Aldolase-catalyzed synthesis of conformationally constrained iminocyclitols: Preparation of polyhydroxylated benzopyrrolizidines and cyclohexapyrrolizidines

Author

Ministerio de Economía y Competitividad (España), Generalitat de Catalunya, Ministerio de Ciencia e Innovación (España), Gobierno de Aragón, Laborda, Pedro, Sayago, Francisco J., Cativiela, Carlos, Parella, Teodor, Joglar Tamargo, Jesús, Clapés Saborit, Pere, Ministerio de Economía y Competitividad (España), Generalitat de Catalunya, Ministerio de Ciencia e Innovación (España), Gobierno de Aragón, Laborda, Pedro, Sayago, Francisco J., Cativiela, Carlos, Parella, Teodor, Joglar Tamargo, Jesús, and Clapés Saborit, Pere

Abstract

A straightforward chemo-enzymatic synthesis of new polyhydroxylated benzopyrrolizidines and cyclohexapyrrolizidines is developed. The two-step strategy consists of l-fuculose-1-phosphate aldolase variant F131A-catalyzed aldol addition of dihydroxyacetone phosphate to rac-N-benzyloxycarbonylindoline- 2-carbaldehyde as well as (2S*,3aS*,7aS*)- and (2S*,3aR*,7aR*)-N-benzyloxycarbonyloctahydroindole-2- carbaldehydes and a subsequent one-step catalytic deprotection-reductive amination. © 2014 American Chemical Society.

Published
2014

230. Aldolase Enzymes for Complex Synthesis

Author

Greenberg, William A., primary, Wong, Chi-Huey, additional, Lemaire, Marielle, additional, Blidi, Lahssen El, additional, Castillo, Jos A., additional, Parella, Teodor, additional, Inoue, Tomoyuki, additional, Sprenger, Georg A., additional, Joglar, Jess, additional, Claps, Pere, additional, Charmantray, Franck, additional, Dellis, Philippe, additional, Hlaine, Virgil, additional, Samreth, Soth, additional, and Hecquet, Laurence, additional

Full Text
View/download PDF

233. Sponge-like molecular cage for purification of fullerenes

Author

García-Simón, Cristina, primary, Garcia-Borràs, Marc, additional, Gómez, Laura, additional, Parella, Teodor, additional, Osuna, Sílvia, additional, Juanhuix, Jordi, additional, Imaz, Inhar, additional, Maspoch, Daniel, additional, Costas, Miquel, additional, and Ribas, Xavi, additional

Published
2014
Full Text
View/download PDF

235. Opposite metabolic responses of shoots and roots to drought

Author

Gargallo-Garriga, Albert, primary, Sardans, Jordi, additional, Pérez-Trujillo, Míriam, additional, Rivas-Ubach, Albert, additional, Oravec, Michal, additional, Vecerova, Kristyna, additional, Urban, Otmar, additional, Jentsch, Anke, additional, Kreyling, Juergen, additional, Beierkuhnlein, Carl, additional, Parella, Teodor, additional, and Peñuelas, Josep, additional

Published
2014
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results