Aldehydes as photoremovable directing groups: synthesis of pyrazoles by a photocatalyzed [3+2] cycloaddition/norrish type fragmentation sequence

A straightforward methodology for the regioselective synthesis of pyrazoles has been developed by a domino sequence based on a photoclick cycloaddition followed by a photocatalyzed oxidative deformylation reaction. Distinguishing features of this protocol include an unprecedented photoredox-catalyzed Norrish type fragmentation under green-light irradiation and the use of α,β-unsaturated aldehydes as synthetic equivalents of alkynes, where the aldehyde is acting as a novel photoremovable directing groupThis work was supported by the MINECO (CTQ2014-53894-R and CTQ2017-85454-C2-2-P) and FEDER/MICIU (PGC2018-098660-B-I00) of Spain. L.O.-R. thanks MINECO for a FPI fellowship, and A.P.-E. thanks CAM for a postdoctoral fellowshi

New reactivity of p-quinols and p-quinones. Synthesis and properties of photoactivatable pyrazolequinones

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Orgánica. Fecha de lectura: 04-12-2019Esta tesis tiene embargado el acceso al texto completo hasta el 04-06-2021The present doctoral thesis has studied different reactivities and properties of p-quinols and pquinones. In the first part of this investigation, it has been carried out the study of a new reactivity of p-quinols in the enantioselective Friedel-Crafts reaction with different heteroaromatic derivatives catalyzed by a BINOL phosphoric acid derivative. As result, it has been achieved for the first time the Friedel-Crafts alkylation compounds with moderate enantioselectivities and excellent diastereoselectivities and therefore accomplished the challenging task of p-quinol desymmetrization. Furthermore, the work has been complemented with computational studies in order to determine the mechanism of the reaction and the absolute configuration of the Friedel-crafts alkylation compounds. The second chapter of this Ph. D. work focusses on the reactivity of quinones with aketoacids. In particular, it has been revealed a double reactivity of the phenylpyruvic acid with naphthoquinone, acting both as a nucleophile as an acylation agent through a domino process that leads to a new synthesis of 3,3-disubstituted naphtho[1,2-b]furan-2(3H)-ones through two Michael type addition reactions followed by a decarboxylative process and an intramolecular lactonization. The optimized reaction was carried out using a wide variety of a-ketoacids and differently substituted quinones. In the first part of the third chapter, another new reactivity of p-quinones has been exhibited, in this case, as dipolarophiles in photoinduced 1,3-dipolar cycloadditions using tetrazoles as precursors of nitrilimine dipoles. This methodology has allowed the synthesis of three different families of pyrazolequinones. After optimization of the reaction conditions a wide scope of both tetrazoles and different benzoindazole-, indazole- or pyrazoleindazolediones has been obtained. Furthermore, in the second part of the third chapter, it has been carried out a detailed study of the photoactivatable properties of the newly synthetized heterocyclic quinones. The spectroscopic study embracing absorption and emission has shown that these compounds absorbs in the blue region and present fluorescence in the orange red one. The electrochemical study performed recording cyclic and square wave voltammetries, together with the estimation of the excited state potentials, has revealed that this new family of quinones significantly increases their oxidizing power by irradiation with blue light, which also triggers singlet oxygen generation. Finally, a study of the biological properties of a selection of quinones was carried out, including cytotoxicity studies in darkness and under irradiation with blue light, as well as studies of subcellular localizationEl trabajo se ha llevado a cabo gracias a la financiación del Ministerio de Economía y Competitividad (MINECO) (Proyectos: CTQ2014-53894-R y CTQ2017-85454-C2-2-P) y a la obtención de una Beca de Formación para Personal Investigador (FPI) del Ministerio de Economía y Competitividad (MINECO)

Friedel–Crafts Alkylation of Indoles with <i>p</i>‑Quinols: The Role of Hydrogen Bonding of Water for the Desymmetrization of the Cyclohexadienone System

Lewis acid catalyzed Friedel–Crafts alkylation of indoles has been achieved in high yields and selectivities using <i>p</i>-quinols as electrophiles. (<i>S</i>)-Binol-3,3′-(9-anthracenyl)-phosphoric acid was able to catalyze the enantioselective formation of 5-(3-indole)-2-cyclohexenone derivatives. Experimental results and theoretical calculations explained the enantioselectivity based on a transition state where two water molecules act as a tether joining the <i>p</i>-quinol with the phosphoric acid and the NH of indole, thus facilitating the desymmetrization of the prochiral cyclohexadienone framework

Ilustración del proceso constructivo de vías primarias, secundarias y terciarias basado en las especificaciones técnicas de construcción de carreteras del Instituto Nacional de vías (INVIAS)

: figuras, tablas ; 28 cmEsta cartilla metodológica describe a través de ilustraciones el proceso constructivo de vías primarias, secundarias y terciarias, basado en las especificaciones técnicas de construcción de carreteras del Instituto Nacional de Vías (INVIAS)PregradoIngeniero CivilIngeniería Civi

Libro de Proyectos Finales 2021 primer semestre

PregradoIngeniero CivilIngeniero de SistemasIngeniero ElectricistaIngeniero ElectrónicoIngeniero IndustrialIngeniero Mecánic