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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Iodine and Copper Catalyzed Oxidative Cross Coupling Reactions : Design and Development of Carbon-Carbon and Carbon-Heteroatom Bond Forming Reactions

Dhineshkumar, J January 2016 (has links) (PDF)
Design and Development of Carbon-Carbon and Carbon-Heteroatom Bond Forming Reactions” is divided into two sections. Section-A, contains two chapters, describes the catalytic ability of iodine for cross coupling reactions. Section-B, divided into three chapters, presents the azidation of organic scaffolds under oxidative conditions. Section A Chapter 1 presents a C-H functionalization of tetrahydroisoquinolines using iodine as a catalyst under aerobic conditions.1 This methodology employs Cross Dehydrogenative Coupling (CDC) strategy as a key step, which is highly atom economical as it doesn’t require pre-functionalized starting materials.2 Owing to the importance of tetrahydroisoquinoline moiety which is present in the umpteen natural products, considerable attention has been put up to functionalize tetrahydroisoquinoline scaffold.3 Iodine a non-metal which is non-toxic was found to catalyze the C-H functionalization of tetrahydroisoquinolines with a variety of nucleophiles such as coumarin, alkyl phosphite, phenols, indoles, acetone and dialkyl malonoates were coupled to it. Significant mechanistic study has been carried out to find the possible intermediate and support the mechanistic proposal. A few representative examples are highlighted in Scheme 1.1 Synopsis Scheme 1: A CDC coupling of tetrahydroisoquinoline with variety of nucleophiles Chapter 2 describes the Cross Hetero Dehydrogenative Coupling (CHDC) reactions of amines, alcohols and sulfoximines with various phosphites.4 Phosphoramidates and phosphate esters are structural scaffolds that are present in a variety of biologically active molecules.5 The conventional methods for synthesizing phosphoramidates/phosphate esters largely involve treating alcohol/amine with appropriate phosphorus halides which generates stoichiometric amount of halogen waste.6 Due to the usage of stoichiometric reagents and difficulties associated with the reported methods, there is a need for developing a protocol which is catalytic and mild. Therefore, we developed a method which employs catalytic amount of iodine and aq. H2O2 as a sole oxidant under milder conditions. Using this methodology, variety of phosphoramidates, phosphorous triesters and sulfoximine derived Synopsis Scheme 2: Phosphorylation of amines, alcohols and sulfoximines phosphoramidates have been synthesized with great efficiency and environmentally benign conditions. A few representative examples are highlighted in Scheme 2.4 Section B Chapter 1 of Section B demonstrates a mild way of synthesizing quaternary azides from α-substituted active methylene compounds which will serve as surrogates for several unnatural amino acid derivatives.7 Azidation has emerged as one of the efficient methods to introduce nitrogen atom in to the organic molecules.8 Azides are versatile functional groups which can be converted to amine, amide, and nitro compounds by simple modification. Moreover, azides are potential handle for “click” chemistry and provide late stage modifications in drug candidates, biomolecules and polymers, etc.9 Azidation of 1,3-dicarbonyl compounds is challenging, as both azides and 1,3-dicarbonyl compounds are nucleophilic in nature. In this section of the thesis, azidation of 1,3-dicarbonyl compounds has been carried out using tetrabutyl ammonium iodide (TBAI) as a catalyst, aq. TBHP as an oxidant and TMSN3 as a azide source. This method uses water as a solvent under mild reaction conditions to generate Synopsis quaternary azides in good to excellent yields. This operationally simple, practical, mild and green method provides an opportunity for synthesizing a variety of azidated β-keto esters, amides and ketones in good yields, Scheme 3.7 The application of this methodology has been demonstrated by synthesising a few triazole and pyrazolone derivatives. Scheme 3: Azidation of 1,3-dicarbonyl compounds Chapter 2 of Section B comprises the azidation and peroxidation of β-napthol derivatives using dearomatization strategy. Azidation and peroxidation are efficient ways to introduce nitrogen and oxygen into organic molecules, which serve as surrogates for amines and alcohol functional groups. In the present study, the azidative or peroxidative dearomatization of naphthol derivatives have been described. The azidation of β-napthol derivatives has been achieved by using CuBr (5 mol %) as a catalyst, TMSN3 as an azide source and aq. TBHP as an oxidant. Whereas, the peroxidation β-napthol derivatives has been accomplished using CuBr (5 mol %) in the presence of aq. TBHP at ambient reaction conditions.10 The products obtained are naphthalenone derivatives, which serve as valuable Synopsis synthetic intermediates and has potential handle for further functionalization.11 Several α-amino or α-peroxy naphthalenones are synthesized using this method in good yields. The usefulness of the methodology has been illustrated by synthesizing a few chiral azides and peroxides in good yields and with moderate enantioselectivity Scheme 4.10 Scheme 4: Dearomatizative azidation and peroxidation of 2-naphthols Chapter 3 reveals the azidation of indole at C-2 position by employing CuBr (10 mol %) as a catalyst and aq. TBHP as an oxidant in acetonitrile under reflux conditions (Scheme 5).12 The C-H functionalization of indole at C-2 position is one of pivotal methods, since it paves a way for synthesizing a variety of indolo-alkaloids.13 Azide is a versatile functionality which can be converted to several other nitrogen containing functional groups such as Synopsis Scheme 5: Azidation of indoles amine, amide, triazole, etc.9 A variety of functional groups were tolerated under the reaction conditions, and furnished the azidated product in good to excellent yields. Through radical inhibition study, we presume that the reaction may be proceeding through radical mechanism. In Scheme 5, a few representative examples are depicted.
2

Production of New Carbon-Heteroatom Bonds Induced by Visible Light

Herrera Luna, Jorge Carlos 05 January 2023 (has links)
[ES] En la presente tesis doctoral se describen metodologías novedosas, simples y rápidas con luz visible para producir compuestos con nuevos enlaces C-heteroátomo como C-B, C-P y C-S que representan estructuras valiosas en la síntesis orgánica moderna. La luz visible se emplea como fuente de energía más suave y sostenible que la tradicional (energía térmica). Por otro lado, también se han empleado nanorreactores espaciales como las redes de gel viscoelástico mediante enfoques 'ascendentes' para mejorar diferentes procesos en comparación con la disolución, en términos de cinética, selectividad o procesabilidad. Por lo tanto, el Capítulo 3 describe un procedimiento novedoso, directo y rápido para producir tiofenos que contienen boro empleando luz visible en disolución anaeróbica sin el uso de ningún fotocatalizador externo. Este estudio se ha ampliado a la borilación de haluros de heteroareno comerciales en condiciones aeróbicas en un nanorreactor de gel fácil de usar (Capítulo 4). La red de gel proporciona un microambiente estabilizador adecuado para soportar una amplia gama de sustratos, incluidos los ésteres de boronato de furano, tiofeno, selenofeno y de pirrol. El Capítulo 5 se centra en una nueva estrategia para lograr una fosforilación aeróbica eficiente de heteroarenos de cinco miembros mediante catálisis fotorredox dicromática en un nanorreactor basado en gel. La metodología, que opera mediante un mecanismo de transferencia de electrones fotoinducida consecutiva (ConPET), se ha aplicado con éxito a la síntesis sencilla y limpia de varios fosfonatos de heteroareno diferentes (furano, tiofeno, selenofeno, pirrol, oxazol o tioxazol), extendiéndose a la etapa tardía de la fosforilación del anticoagulante rivaroxabán. Por último, el Capítulo 6 muestra una tiolación (formación enlaces C-S) simple y efectiva, libre de metales, de haluros de heteroareno comerciales usando luz visible. Los resultados experimentales son consistentes con una reacción basada en un complejo aceptor-donador de electrones (EDA) entre una alquilamina y el haluro de heteroareno. El mecanismo del proceso se ha demostrado mediante estudios espectroscópicos, mientras que la robustez se ha demostrado mediante experimentos a escala de gramo y derivatización de última etapa. / [CA] En la present tesi doctoral es descriuen metodologies noves, simples i ràpides amb llum visible per a produir compostos amb nous enllaços C-heteroàtom com C-B, C-P i C-S que representen estructures valuoses en la síntesi orgànica moderna. La llum visible s'utilitza com a font d'energia mes suau i sostenible que la tradicional (energia tèrmica). D'altra banda, també s'han emprat nanorreactors espacials com les xarxes de gel viscoelàstic mitjançant enfocaments 'ascendents' per a millorar diferents processos en comparació amb la dissolució, en termes de cinètica, selectivitat o procesabilitat. Per tant, el Capítol 3 descriu un procediment nou, directe i ràpid per a produir tiofens que contenen bor emprant llum visible en dissolució anaeròbica sense l'ús de cap fotocatalitzador extern. Aquest estudi s'ha ampliat a la borilació d'halurs d'heteroaré comercials en condicions aeròbiques en un nanorreactor de gel fàcil d'usar (Capítol 4). La xarxa de gel proporciona un microambient estabilitzador adequat per a suportar una àmplia gamma de substrats, inclosos els èsters de boronat de furan, tiofé, selenofé i de pirrol. El Capítol 5 se centra en una nova estratègia per a aconseguir una fosforilació aeròbica eficient de heteroarens de cinc membres mitjançant catàlisis fotorredox dicromàtica en un nanorreactor basat en gel. La metodologia, que opera mitjançant un mecanisme de transferència d'electrons fotoinducida consecutiva (ConPET), s'ha aplicat amb èxit a la síntesi senzilla i neta de diversos fosfonats d'heteroaré diferents (furan, tiofé, selenofé, pirrol, oxazol o tioxazol), estenent-se a l'etapa tardana de la fosforilació de l'anticoagulant rivaroxabán. Finalment, el Capítol 6 mostra una tiolació (formació d'enllaços C-S) simple i efectiva, lliure de metalls, d'halurs d'heteroaré comercials usant llum visible. Els resultats experimentals són consistents amb una reacció basada en un complex acceptor-donador d'electrons (EDA) entre una alquilamina i l'halur d'heteroaré. El mecanisme del procés s'ha demostrat mitjançant estudis espectroscòpics, mentre que la robustesa s'ha demostrat mitjançant experiments a escala de gram i derivatització d'última etapa. / [EN] This thesis doctoral describes novel, simple, and rapid methodologies using visible light to produce compounds with new C-heteroatom bonds such as C-B, C-P and C-S that represent valuable scaffolds in modern organic synthesis. The employment of visible light as energy source highlights the concepts of green and sustainable chemistry considering its mild, safe, and eco-friendly advantages. On the other hand, spatially nanoreactors such as viscoelastic gel networks by 'bottom-up' approaches to improve different processes in comparison to solution, in terms of kinetics, selectivity or processability have been also developed. Thus, Chapter 3 describes a novel, straightforward, and fast procedure to produce boron-containing thiophenes employing visible light in anaerobic solution. Interestingly, the process does not require the use of any external photocatalyst. This study has been extended to the borylation of commercially available heteroarene halides under aerobic conditions in an easy-to-use gel nanoreactor (Chapter 4). The gel network provides an adequate stabilizing microenvironment to support wide substrate scope, including furan, thiophene, selenophene, and pyrrole boronate esters. Chapter 5 focus on a new strategy to achieve efficient aerobic phosphorylation of five-membered heteraroenes using dichromatic photoredox catalysis in a gel-based nanoreactor. The methodology, which operates by a consecutive photoinduced electron transfer (ConPET) mechanism, has been successfully applied to the straightforward and clean synthesis of a number of different heteroarene (furan, thiophene, selenophene, pyrrole, oxazole, or thioxazole) phosphonates, extending to the late-stage phosphonylation of the anticoagulant rivaroxaban. Lastly, regarding the construction of new C-S bonds, Chapter 6 shows a simple and effective metal-free thiolation of commercial heteroarene halides using visible light. The experimental results are consistent with the reaction taking place from an electron donor-acceptor (EDA) complex between an alkylamine and the heteroarene halide. Mechanistic aspects of the whole process have been demonstrated by spectroscopic measurements whereas the strength of this novel method has been proven by gram-scale experiment and late-stage derivatization. / Herrera Luna, JC. (2022). Production of New Carbon-Heteroatom Bonds Induced by Visible Light [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/191051
3

Développement de nouvelles réactions métallo-catalysées pour la création de liaisons C-C et C-hétéroatomes : Application à la synthèse d’inhibiteurs de la Hsp90 et aux ligands de la lectine A. / New metal-catalyzed methodologies for C-C and C-heteroatom bond-forming reactions : Application to the synthesis of Hsp90 inhibitors and Lectine A ligands.

Bruneau, Alexandre 11 December 2015 (has links)
Les travaux rapportés dans ce mémoire concernent le développement de nouvelles réactions métallo-catalysées pour la création de liaison carbone-hétéroatome et carbone-carbone ainsi que leurs applications à la synthèse de produits biologiquement actifs. La première partie de ce manuscrit est consacrée à l'étude de la réactivité des sucres dans les couplages organométalliques. Des conditions ont été développées pour la création de la liaison C-S entre glycosyl thiols et partenaires arylés. De plus, la création de la liaison carbone azote de glycosyl amines avec des acides boroniques a été étudiée. Les produits synthétisés dans cette première partie ont été évalués pour leur potentiel d'inhibition de la Lectine A chez Pseudomonas aeruginosa, impliquée dans de sévères infections pulmonaires.La seconde partie de ce travail est dédiée à la création d'une série inédite d'analogues du 6BrCaQ, inhibiteurs de la Hsp90 ainsi que leur évaluation biologique. Cette nouvelle série est obtenue grâce à une nouvelle méthodologie de synthèse basée sur l'activation C-H entre un hétérocycle halogéné et son partenaire C-H activable. L'activité antiproliférative et l'inhibition de la Hsp90 ont été évaluées et seront présentées dans ce manuscrit. / The work reported in this dissertation concerns the development of new metal-catalyzed reactions for the creation of carbon-heteroatom and carbon-carbon bonds as well as their applications to the synthesis of biologically active products.The first part of this manuscript is devoted to the study of the reactivity of sugars as nucleophiles in organometallic couplings. Conditions were developed for the creation of the C-S bond between glycosyl thiols and aryl partners. Moreover, the creation of the nitrogen carbon bond of glycosyl amine with boronic acids was studied. The products synthesized in this first part have been evaluated for their potential to inhibit the lectin A, in Pseudomonas aeruginosa related lung infections.The second part of this work is dedicated to the creation of a new series of 6BrCaQ analogues as Hsp90 inhibitors and their biological evaluation. This new series was synthetized through a new CH activation methodology. The antitumoral potential was evaluated and will be presented in this manuscript.
4

Studies towards Developing Diastereoselective SN1 Reactions of α-Keto Carbocations

Dubland, Joshua 06 April 2010 (has links)
Although α-keto carbocations have been demonstrated to be viable intermediates in solvolysis reactions, their applications in synthesis are scarce. These species can be considered to be equivalent to “reversed polarity” enolates and, as such, could be useful for the asymmetric formation of carbon-carbon and carbon-heteroatom bonds. In principle, facial selectivity in additions to α-keto carbocations may be induced using easily removed ester, amide, or imide chiral auxiliaries. Efforts to achieve such diastereoselective SN1 reactions of α-keto carbocations are described herein.
5

Studies towards Developing Diastereoselective SN1 Reactions of α-Keto Carbocations

Dubland, Joshua 06 April 2010 (has links)
Although α-keto carbocations have been demonstrated to be viable intermediates in solvolysis reactions, their applications in synthesis are scarce. These species can be considered to be equivalent to “reversed polarity” enolates and, as such, could be useful for the asymmetric formation of carbon-carbon and carbon-heteroatom bonds. In principle, facial selectivity in additions to α-keto carbocations may be induced using easily removed ester, amide, or imide chiral auxiliaries. Efforts to achieve such diastereoselective SN1 reactions of α-keto carbocations are described herein.
6

Metal nanoparticles stabilized by alkaloids in glycerol : from design to catalytic applications / Nanoparticules métalliques stabilisées par des alcaloïdes dans le glycérol : du design à l’application en catalyse

Reina Tapia, Antonio 03 October 2017 (has links)
Les nanoparticules métalliques (MNPs) ont un grand succès dans les dernières décennies dû à la variété d'applications dans différents domaines (microélectronique, matériaux, catalyse). Mis à part les solvants organiques, les liquides ioniques, l'eau, le CO2 supercritique et les polyols, en particulier le glycérol, ont démontré leur capacité à stabiliser et immobiliser les nanoparticules métalliques. Ces milieux évitent l'agglomération des MNPs et facilitent leur recyclage. Des nanoparticules de Pd(0) et Ni(0) dans le glycérol, sphériques, petites en taille et bien dispersées, ont été synthétisées avec succès à partir d'une méthodologie simple sous pression d'hydrogène, en présence de différents stabilisants (alkaloïdes, phosphine, polymer). La caractérisation complète de ces matériaux en solution et à l'état solide, ainsi que la possibilité de faire des synthèses à grande échelle et de stocker les solutions catalytiques longtemps, montrent la grande stabilité de ces solutions colloïdales. Les nanoparticules dans le glycérol ont été impliquées dans une large variété de transformations : hydrogénations, hydrodéhalogénations, couplages de Hiyama, additions conjuguées et hydrosilylations. De plus, nous avons étudié l'effet du stabilisant sur la réactivité catalytique, nous permettant de contrôler l'état de surface des nanoparticules et moduler ainsi leur réactivité. Nous avons montré, de même, la capacité du glycérol pour immobiliser les catalyseurs, ce qui s'est traduit par la possibilité de recycler la phase catalytique entre 4 et 10 fois sans perte de metal. En parallèle, nous avons évalué le comportement du Ni(OAc)2 libre de ligands dans le glycérol, en tant que catalyseur alternatif pour des couplages C-C et C-hétéroélément. Nous présentons aussi une étude en flux continu, en collaboration avec la Maison Européenne des Procédés Innovants (MEPI), pour l'hydrogénation de différents groupes fonctionnels, en utilisant les PdNPs dans le glycérol synthétisées préalablement. / Metal nanoparticles (MNPs) have been largely studied in the last decades due to their interesting properties which found applications in several fields (microelectronics, materials and catalysis, among others). In contrast to common organic solvents, ionic liquids, water, supercritical CO2, polyols such as glycerol, represent innovative solvents for the immobilization of MNPs, avoiding their agglomeration and facilitating their recycling. Small, spherical, and well-dispersed Pd(0) and Ni(0) nanoparticles were synthesized under hydrogen pressure in glycerol, in the presence of different kinds of stabilizers (cinchona-based alkaloids, phosphine, polymer). The high stability of these colloidal solutions permitted the full characterization both in solution and at solid state, large-scale synthesis, and stocking the solutions for months. These colloidal catalysts were applied in a large variety of transformations including hydrogenations, hydrodehalogenations, Hiyama C-C couplings, hydrosilylation reactions, and Michael conjugate additions. Furthermore, we conducted a comparative study exhibiting the differences in catalytic reactivity by effect of the stabilizer, allowing us tuning the surface-state of the nanoparticles. Moreover, we showed the ability of glycerol to immobilize metal nanoparticles permitting the recycle of the catalytic phase between 4 and 10 times, without metal leaching. Additionally, we studied the behavior of ligand-free Ni(OAc)2 in glycerol as an alternative catalyst for C-C and C-heteroatom couplings. Also, we developped a continuous flow study, in collaboration with the Maison Européenne des Procédés Innovants (MEPI), for the hydrogenation of different functional groups, using PdNPs in glycerol
7

Propriétés et performances de phosphines ferrocéniques dans le couplage C-O, C-S et C-N : nouvelles méthodologies de synthèse au palladium / Properties and performance of ferrocenyl phosphanes in C-O, C-S and C-N cross coupling reactions : palladium catalized new methodologies

Platon, Mélanie 23 July 2012 (has links)
Les ligands multidentes montrent généralement de très bonnes activités dans la catalyse organométallique au palladium à faibles charges. Parmi ces ligands, l'utilisation des ligands polyphosphines ferrocéniques mènent à des résultats intéressants. Des systèmes catalytiques palladium/triphosphine ferrocénique robustes ont permis d'obtenir d'une part des diarylamines et d'autre part des éthers d'aryle et d'hétéroaryle avec de faibles charges catalytiques. Des calculs théoriques de DFT sur le cycle catalytique lors de la formation d'éthers d'aryle et d'hétéroaryle ont été réalisés. La présence d’un troisième groupement phosphino permettrait de stabiliser les états de transition et accélèrerait l’élimination réductrice. Les triarylamines ont pu être obtenues à l'aide d'une diphosphine ferrocénique avec une charge de 2 mol% de palladium. Des résultats modérés à excellents ont été obtenus. Enfin, les thioéthers d'aryle et d'hétéroaryle ont été obtenus avec d'excellents résultats à l'aide d'une tétraphosphine ferrocénique en présence de 0,2 mol% de palladium / Multidentate ligands usually show great activities in low loading organometallic catalysis in palladium. Among these ligands, the use of ferrocenyl polyphosphane ligands give interesting results. Robust palladium-ferrocenyl triphosphane catalytic systems have permitted to obtain biarylamines and aryl-heteroaryl ethers in the presence of low catalytic loadings. DFT studies on catalytic cycle during formation of aryl-heteroaryl ethers were carried out. The presence of third phosphino group stabilizes a transition state which enhances the rate of the reductive elimination. Triarylamines were obtained with ferrocenyl diphosphane in the presence of 2 mol% of palladium loading. Moderate to excellent results were obtained. Finally, aryl-heteroaryl sulfides were obtained with excellent results with ferrocenyl tetraphosphane ligand in the presence of 0.2 mol% of palladium.
8

Reactivity of well-defined organometallic copper(III) complexes in carbon-heteroatom bond forming reactions

Casitas Montero, Alícia 01 June 2012 (has links)
This thesis is focused on the unexplored field of organometallic copper(III) chemistry. Arylcopper(III) complexes have been proposed as key intermediates in Ullmann condensation reactions that consist in the coupling of aryl halides and heteroatom nucleophiles catalyzed by copper. The study of the reactivity of well-defined arylcopper(III) complexes may provide a better understanding of the mechanism of Ullmann condensation reactions, which is still under intense debate. In this doctoral dissertation we study the feasibility of well-defined arylcopper(III) complexes, which are stabilized within macrocyclic ligands, to participate in C-heteroatom bond forming reactions. We develop copper-catalyzed C-N and C-O bond forming reactions, as well halide exchange reactions, including fluorinations, based on Cu(I)/Cu(III) catalytic cycle within model aryl halide substrates. We uncover the fundamental understanding of the two-electron redox steps, oxidative addition and reductive elimination, at copper. / Aquesta tesi es centra en el camp de la química organometàl•lica del coure(III) que roman sense explorar. Els complexos arilcoure(III) s'han proposat com a intermedis clau en les reaccions de condensació Ullmann que consisteixen en l'acoblament d'halurs d'arils i nucleòfils basats en heteroàtoms catalitzades amb coure. L'estudi de la reactivitat de complexos arilcoure(III) ben definits pot proporcionar una millor comprensió del mecanisme de les reaccions de condensació Ullmann, el qual es troba sota un intens debat. En aquesta tesi doctoral s'estudia la viabilitat del complexos arilcoure(III), estabilitzats en lligands macrocíclics, de participar en reaccions de formació d'enllaç carboni-heteroàtom. S'han desenvolupat reaccions de formació d'enllaç C-N i C-O així com reaccions d'intercanvi d'halurs, on s'inclouen fluoracions, catalitzades amb coure i basades en un cicle catalític Cu(I)/Cu(III) utilitzant substrats models d'halur d'aril. S'ha obtingut una comprensió fonamental de les etapes redox a dos electrons, addició oxidant i eliminació reductiva, en coure.

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