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1,632 results on '"Castedo, Luis"'

201. RCM for the construction of novel steroid-like polycyclic systems. 1. Studies on the synthesis of a PreD3-D3 transition state analogue

Author

Garcia-Fandino, Rebecca, Jose, Maria, Aldegunde, Jose, Codesido, Eva M., Castedo, Luis, and Granja, Juan R.

Subjects
Polycyclic compounds -- Structure, Polycyclic compounds -- Chemical properties, Ring formation (Chemistry) -- Analysis, Biological sciences, Chemistry
Abstract

A new strategy by which complex polycyclic steroid-like systems could be constructed on the steroid CD framework, by a combination of ring-closing metathesis (RCM) and Herck cyclization is described. The method is exemplified by its application to the stereoselective synthesis of 6-8-6 fused carbocyclic systems that mimic the putative transition structure of the isomerization of previtamin D3 to vitamin D3.

Published
2005

202. First stereoselective syntheses of (--)-siphonodiol and (--)-tetrahydrosiphonodiol, bioactive polyacetylenes from marine sponges

Author

Lopez, Susana, Fernandez-Trillo, Francisco, Midon, Pilar, Castedo, Luis, and Saa, Carlos

Subjects
Polyacetylene -- Chemical properties, Sponges -- Research, Chemical synthesis, Biological sciences, Chemistry
Abstract

The first stereoselective total syntheses of the bioactive marine polyacetylenes (--)-siphonodiol and (--)-tetrahydrosiphonodiol were achieved using highly convergent approaches based on optimized Cadiot-Chodkiewicz and sequential Sonogashira cross-coupling reactions. It was envisioned that both metabolites could be constructed from the di-cis-dibromodienes following a common strategy that would imply stereoselective sequential sp(super 2)--sp cross-coulping reactions.

Published
2005

217. Ruthenium-catalyzed [3 + 2] intramolecular cycloaddition of alk-5-ynylidenecyclopropanes promoted by the 'first-generation' Grubbs carbene complex

Author

Lopez, Fernando, Delgado, Alejandro, Rodriguez, Ramon, Castedo, Luis, and Mascarenas, Jose L.

Subjects
Ring formation (Chemistry) -- Research, Ruthenium -- Research, Ruthenium -- Chemical properties, Chemistry
Abstract

The first [3C + 2C] cycloaddition process catalyzed by a ruthenium complex constituting a novel nonmetathetic application of the Grubbs carbene complex is reported. The desired cycloadduct to the reaction was obtained in 11% and 35% yields respectively.

Published
2004

222. A theoretical rationalization of the asymmetric induction in sulfinyl-directed [5C + 2C] intramolecular cycloadditions

Author

Lopez, Fernando, Castedo, Luis, and Mascarenas, Jose L.

Subjects
Ring formation (Chemistry) -- Research, Biological sciences, Chemistry
Abstract

The thermal cycloadditions of 6-acetoxy-3-pyranones and 3-silyloxy-4-pyrones with tethered alkenyl sulfoxides is examined by using computational DFT. It confirms that the high level of diastereofacial selectivity obtained is due to the preference of the alkenesulfinyl group to adopt a well-defined conformation in the transition state of the reaction.

Published
2003

223. Scope of Ru(II)-catalyzed synthesis of pyridines from alkynes and nitriles

Author

Varela, Jesus A., Castedo, Luis, and Saa, Carlos

Subjects
Ring formation (Chemistry) -- Research, Pyridine -- Research, Nitriles -- Research, Biological sciences, Chemistry
Abstract

Pyridines can be efficiently synthesized by Ru(II)-catalyzed [2 +2 + 2] cycloaddition of 1,6-diynes to alpha, omega-dinitriles or electron-deficient nitriles. The reaction with asymmetric electron-deficient alkynes provides 2,3,6-trisubstituted pyridines in good yield.

Published
2003

224. Synthesis of polyhydroxycyclohexanes and relatives from (-)-quinic acid

Author

Gonzalez, Concepion, Carballido, Montserrat, and Castedo, Luis

Subjects
Chemistry, Organic -- Research, Acids -- Composition, Cyclic compounds -- Composition, Lactones, Biological sciences, Chemistry
Abstract

Research has been conducted on polyhydroxycyclohexanes. The authors describe the strategy developed for the synthesis of these and related compounds whcih has been carried out via quinic acid derived lactone.

Published
2003

225. Cyclic allene intermediates in itramolecular dehydro Diels-Alder reactions: labeling and theoretical cycloaromatization studies

Author

Rodriguez, David, Navarro-Vazquez, Armando, Castedo, Luis, Dominguez, Domingo, and Saa, Carlos

Subjects
Chemistry, Organic -- Research, Cyclic compounds -- Composition, Organic compounds -- Composition, Diels-Alder reaction -- Analysis, Hydrogen, Radicals (Chemistry), Biological sciences, Chemistry
Abstract

Research has been conducted on dehydro Diels-Alder reactions. The study of the cyclic allene intermediate evolution carried out via theoretical and experimental investigation of these dehydro Diels-Alder reactions in order to examine intramolecular, ionic and radical intermolecular cycloaromatization processes is presented.

Published
2003

227. Selective palladium-catalyzed cocyclotrimerization of arynes with dimethyl acetylenedicarboxylate: A versatile method for the synthesis of polycyclic aromatic hydrocarbons

Author

Pena, Diego, Perez, Dolores, Guitian, Enrique, and Castedo, Luis

Subjects
Palladium catalysts -- Chemical properties, Biological sciences, Chemistry
Abstract

Benzyne and substituted derivatives can be efficiently cyclotrimerized to the corresponding triphenylenes by palladium(0) catalysts while the extension of this reaction to polycyclic arynes provides straightforward access to complex polycyclic aromatic hydrocarbons (PAHs).

Published
2000

240. A MATLAB Interface for Analyzing Conformal Arrays Composed of Polarized Heterogeneous Elements

Author

Brégains, Julio, García-Naya, José A., González-López, Miguel, and Castedo, Luis

Subjects
Graphical user interface, Conformal arrays, Array polarization, Antenna polarization, Heterogeneous arrays, Antenna arrays, Antenna radiation patterns, Conformal antennas
Abstract

[Abstract] As an extension and improvement of a previous work, this paper presents a graphical interface designed with MATLAB®, which is capable of representing both the spatial and electrical configurations of a conformal antenna array, as well as the different patterns radiated by the array. The tool considers the polarization of the elements of the array, which are not necessarily congruent to each other.

Published
2011

241. A WiMAX Conformal Broad-Beam Antenna

Author

Brégains, Julio, Castedo, Luis, and Ares Pena, F. J.

Subjects
WiMax, Microwave antennas, Antenna radiation patterns, Conformal antennas
Abstract

[Abstract] The numerical model of a very simple conformal antenna, prepared to work in the 3.4 to 3.6 GHz WiMAX range, is presented. The pattern radiated by the proposed antenna displays high gain and excellent linear polarization within the broad coverage zone. Xunta de Galicia; 09TIC008105PR Xunta de Galicia; 07TIC002206PR Ministerio de Ciencia e Innovación; TEC2007-68020-C04-01 Ministerio de Ciencia e Innovación; TEC2008-04485 Ministerio de Ciencia e Innovación; CSD2008-00010.

Published
2010

248. LTE Downlink Performance in High Speed Trains

Author

Rodriguez-Pineiro, Jose, primary, Suarez-Casal, Pedro, additional, Lerch, Martin, additional, Caban, Sebastian, additional, Garcia-Naya, Jose A., additional, Castedo, Luis, additional, and Rupp, Markus, additional

Published
2015
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