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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.
291

Palladium-catalyzed directed introduction of α-CF3-vinyl and SCF3 groups by C-H bond functionalization / Introduction dirigée de motifs α-CF3-vinyliques et SCF3 par fonctionnalisation de liaisons C-H, catalysée au palladium

Zhao, Qun 11 December 2017 (has links)
Ces dernières années ont été témoin de l'énorme développement de la chimie organique du fluor. Notamment, l'introduction de groupements fluorés émergents sur des « briques » moléculaires variées a attiré l'attention de la communauté scientifique en raison de leurs propriétés particulières. De plus, la stratégie de fonctionnalisation dirigée de la liaison C-H par catalyse par les métaux de transition, a conduit à une révolution dans le développement de méthodologies synthétiques originales. Par conséquent, la conception de nouvelles approches synthétiques pour l'introduction de groupements fluorés par fonctionnalisation de la liaison C-H catalysée par les métaux de transition est particulièrement attirante. Dans cette thèse, nous nous sommes concentrés sur le développement de nouvelles méthodologies d'introduction directe des groupements fluorés sur des arènes et des oléfines par fonctionnalisation directe de liaison C(sp2)-H catalysée par les métaux de transition. En particulier, nous avons tourné notre attention sur le 2-bromo-3,3,3-trifluoropropène (BTP), un réactif fluoré bon marché et provenant de déchets de l'industrie. Ce dernier est utilisé comme agent de remplacement de halon pour la suppression des incendies et, utilisé comme « brique » moléculaire en synthèse organique (Chapitre 1). La première partie de cette thèse est dédiée au développement de nouvelles méthodologies pour l'introduction directe du groupement CF3-vinyl sur des arènes et des oléfines par fonctionnalisation de la liaison C(sp2)-H catalysée par le palladium. Ensuite, cette approche a été étendue à la fonctionnalisation d'esters α,β- insaturés, bien qu'un mécanisme différent soit probablement impliqué (Chapitre 2). Dans la seconde partie de cette thèse, nous avons développé une nouvelle méthodologie pour l'introduction directe du groupement SCF3 sur des arènes et des oléfines par fonctionnalisation de la liaison C(sp2)-H catalysée par le palladium, utilisant le réactif de Munavalli (Chapitre 3). / Recent years have witnessed a great development of the organofluorine chemistry field. In particular, the introduction of emergent fluorinated moieties onto various scaffolds has attracted attention of the scientific community because of their special properties. Besides, transition metal-catalyzed directed C-H bond functionalization strategy has brought a revolution in the development of original synthetic methodologies, since it allows straightforward and more atom-economical processes. Thus, the design of new synthetic approaches for the introduction of fluorinated moieties by transition metal-catalyzed C-H bond functionalization pathway is particularly appealing. Therefore, in this Ph.D. thesis, we focused on the development of new methodologies for the direct introduction of fluorinated moieties onto arenes and olefins by transition metal catalyzed directed C(sp2)-H bond functionalization. In particular, we turned our attention to the 2-bromo-3,3,3-trifluoropropene (BTP), an inexpensive fluorinated reagent coming from industry waste, used as a potential halon replacement for fire suppression and as a fluorinated building block in organic synthesis (Chapter 1). The first part of this Ph.D. thesis was dedicated to the development of new methodologies for the direct introduction of a CF3- vinyl moiety onto arenes and olefins by a Pd-catalyzed directed C(sp2)-H bond functionalization with BTP. Then, this approach was extended to the functionalization of α,β-unsaturated esters, although a different reaction pathway is probably involved (Chapter 2). In the second part of this Ph.D. thesis, we developed a new methodology for the direct introduction of the SCF3 group onto arenes and olefins by Pd-catalyzed directed C(sp2)-H bond functionalization using the Munavalli reagent (Chapter 3).
292

Synthèse d'hétérocycles fluorées / Synthesis of fluorine-containing heterocycles

Tran do, Minh Loan 05 December 2018 (has links)
Les fluoroalcènes sont employés pour préparer des mimes de peptides. Malgré de nombreuses études réalisées dans ce domaine, la préparation d'analogues de peptides comportant une proline modifiée en position C-terminale a été très peu explorée. Ce travail de thèse est consacré à la synthèse de pyrrolidine comportant un motif fluorovinylique. La préparation de sulfones fluorées comportant un cycle pyrrolidine a été réalisée, par réaction d'aza-Michael intramoléculaire. Ce réactif permet la formation de pyrrolines par réaction de Julia modifiée, là où la réaction de Horner-Wadworth-Emmons échoue. Cette étude a été étendue à la préparation de pipéridines fluorées. Cette méthode a été appliquée avec succès à la préparation de précurseurs de peptides Pro-Ψ[CF=CH]-Xaa, peu étudiés dans la littérature. / Fluoroalkenes are used to prepare peptide mimics. In spite of numerous studies carried out in this field, the preparation of peptide analogs comprising a modified proline in the C-terminal position has been very little explored. This thesis is devoted to the synthesis of pyrrolidine with a fluorovinyl unit. The preparation of fluorinated sulfones containing a pyrrolidine ring was carried out by reaction of intramolecular aza-Michael. This reagent allows the formation of pyrrolines by modified Julia reaction, where the Horner-Wadworth-Emmons reaction fails. This study was extended to the preparation of fluorinated piperidines. This method has been successfully applied to the preparation of pro-Ψ peptide precursors [CF = CH] -Xaa, which are poorly studied in the literature.
293

Syntéza a reaktivita hypervalentních fluoridů síry / Synthesis and reactivity of hypervalent sulfur fluorides

Ajenjo, Javier January 2019 (has links)
The pentafluorosulfanyl (SF5) group displays remarkable and unique properties, including large dipole moment, high electronegativity, high thermal and chemical stability, as well as high lipophilicity. However, only a few synthetic methods for the preparation of aromatic pentafluorosulfanyl building blocks have been developed to date. This work aims at improving availability and accessibility of aryl sulfurpentafluoride building blocks. In the first part of the work, the synthesis of aryl sulfurpentafluorides by the direct fluorination of diaryl disulfides with elemental fluorine is described. Nowadays, this synthetic strategy is used by industry on a multi-kilogram scale. However, the scope of the reaction is only limited to 3- and 4- nitro-1-(pentafluorosulfanyl)benzenes. In this work, the synthesis of various para-, meta- and ortho-substituted-(pentafluorosulfanyl)benzenes following the same approach was carried out. In the second part, the derivatization of aryl sulfurpentafluoride building blocks was investigated. Direct fluorination of 3-nitro-1-(pentafluorosulfanyl)benzene afforded 3-fluoro-5-nitro-1- (pentafluorosulfanyl)benzene. The titled compound was derivatized by two different processes: nucleophilic aromatic substitution (SNAr) of fluorine and vicarious nucleophilic substitution of...
294

Vers l'introduction douce de groupes fluorés émergents oxygénés et soufrés / New methodologies to introduce emerging fluorinated groups oxygenated and sulphurinated

Bouvet, Sébastien 18 November 2015 (has links)
Les travaux s’articulent autour du développement de nouveaux agents de fluoration et sur l’étude de leurs réactivités au cours de différentes réactions.Dans une première partie, nous décrivons la synthèse de nouvelles sources réactives de fluorure à partir de liquides ioniques de type imidazolium possédant un fluor en partie anionique. Les deux liquides ioniques [bmim][F] et [bdmim][F] obtenus ont ensuite été testés dans différents processus de monofluoration et de fluorodésulfuration oxydative.Une deuxième partie concerne le développement de réactifs de trifluorométhoxylation.Dans un premier temps, nous nous sommes attachés à synthétiser des nouveaux précurseurs de carbène possédant un groupement OCF3. Nous avons ensuite évalué leur réactivité au cours de différents processus. Dans un second temps, nous nous sommes axés sur la réactivité d’un composé FAR (Fluoroalkyl Amino Reagent) dans des réactions d’acylation aromatique.Enfin, le dernier chapitre rapporte l’étude du comportement électrochimique en réduction du gaz SF6, le but étant d’obtenir une nouvelle source radicalaire de SF5. Après une première partie analytique, l’hexafluorure de soufre a été engagé dans des processus d’électrosynthèse pour tenter de piéger les intermédiaires réactionnels issus de sa réduction. / The manuscript deals the development of new fluorinating reagents and their reactivity in various reactions.In the first part, we were interested in developing new fluoride sources from ionic liquids with imidazolium as the cationic part, and associated to the fluoride as anion. Two ionic liquids, [bmim][F] and [bdmim][F], were obtained. They were then tested in monofluoration and fluorodesulfurization reactions.The second chapter concerns the development of new trifluoromethoxylation reagents.We began by synthetizing new carbene precursors with an OCF3 group. We then evaluated their reactivities in different processes. A second part was centered on a FAR compound and its reactivity in aromatic acylation reactions.Finally, the last chapter describes the behavior of SF6 in electrochemistry reduction with different conditions, the aim being to have a new source of SF5 radical. After a first part concerning analytical studies of the sulfur hexafluoride, the aforementioned compound was engaged an electrosynthetic process to trap intermediate species coming from its reduction.
295

A Multiwire Proportional Chamber Positron Camera for Studies of the Intracerebral Dopamine Metabolism

Durocher, Joseph Jean Guy 08 1900 (has links)
Part A of two Project Reports; Part B can be found at http://hdl.handle.net/11375/17660 / <p> The recent development of a technique for the synthesis of the molecule 5-(¹⁸F) fluoro-dopa has opened a vast field of research into the study of the intracerebral metabolism. In order to take full advantage of this new tracer compound it will be necessary to use an imaging system which will be capable of providing three dimensional information concerning the rapid changes in activity as the ¹⁸F travels through the brain. This report describes the results os investigations into a possible design for a device which would be capable of this type of dynamic imaging. The design in question employs multiwire proportional chambers (MWPC) as detectors of the .511 MeV gamma rays which result from the annihilation of the positron emitted in the decay of ¹⁸F. </p> <p> For comparison purposes, a breif review of various other types of positron tomographic systems which are presently in use or under development is presented. This review emphasises the resolution, data aquisition speed, and instalation cost for each of these designs. </p> <p> In order to eliminate the need for costly research into the various design aspects of multiwire proportional chambers for use with positron annihilation radiation, the design presented here relies exclusively on methods and designs developed and proven feasible by other groups. These are incorporated into a system to suit the present needs. </p> <p> The design presented uses two pairs of 50x50 cm² MWPC's at 180° to each other and separated by approximately 50 cm. The chambers utilize electromagnetic delay-line readout techniques for the anode and wound bi-filar cathode planes. They are filled with a "magic gas" mixture at a slightly positive pressure. The effeciency of the chambers for .511 MeV photons is increased by employing "sandwich" type converters. Signals from the detectors are transfered to a small computer where they are stored for later tomographic reconstruction off-line. </p> <p> On the basis of the working designs from which the present design has been drawn, one would expect the positron camera to have a sensitivity of better than 1000 counts/second-microcurie. The total costs of development and construction leading up to a working device suitable for clinical use, not including the cost of a dedicated computer, are estimated to be less than seventy five thousand dollars. </p> / Thesis / Master of Engineering (ME)
296

Improved Anticancer Activities of a New Pentafluorothio-Substituted Vorinostat-Type Histone Deacetylase Inhibitor

Goehringer, Nils, Peng, Yayi, Nitzsche, Bianca, Biermann, Hannah, Pradhan, Rohan, Schobert, Rainer, Herling, Marco, Höpfner, Michael, Biersack, Bernhard 08 May 2023 (has links)
The development of new anticancer drugs is necessary in order deal with the disease and with the drawbacks of currently applied drugs. Epigenetic dysregulations are a central hallmark of cancerogenesis and histone deacetylases (HDACs) emerged as promising anticancer targets. HDAC inhibitors are promising epigenetic anticancer drugs and new HDAC inhibitors are sought for in order to obtain potent drug candidates. The new HDAC inhibitor SF5-SAHA was synthesized and analyzed for its anticancer properties. The new compound SF5-SAHA showed strong inhibition of tumor cell growth with IC50 values similar to or lower than that of the clinically applied reference compound vorinostat/SAHA (suberoylanilide hydroxamic acid). Target specific HDAC inhibition was demonstrated by Western blot analyses. Unspecific cytotoxic effects were not observed in LDH-release measurements. Pro-apoptotic formation of reactive oxygen species (ROS) and caspase-3 activity induction in prostate carcinoma and hepatocellular carcinoma cell lines DU145 and Hep-G2 seem to be further aspects of the mode of action. Antiangiogenic activity of SF5-SAHA was observed on chorioallantoic membranes of fertilized chicken eggs (CAM assay). The presence of the pentafluorothio-substituent of SF5-SAHA increased the antiproliferative effects in both solid tumor and leukemia/lymphoma cell models when compared with its parent compound vorinostat. Based on this preliminary study, SF5-SAHA has the prerequisites to be further developed as a new HDAC inhibitory anticancer drug candidate.
297

Development of Novel Visible and Solar Light-Activated Nanostructured Nitrogen-Fluorine Titanium Dioxide Photocatalyst for the Removal of Cyanotoxins in Water

Pelaez, Miguel 23 October 2012 (has links)
No description available.
298

Photocyclodehydrofluorination (PCDHF) –A synthetic method for fluorinated polynuclear aromatic hydrocarbons

LI, ZHE 01 December 2015 (has links)
No description available.
299

Development of Fluorinated Non-Peptidic Ghrelin Receptor Ligands for Potential Use in Molecular Imaging

Moldovan, Rares-Petru, Els-Heindl, Sylvia, Worm, Dennis J., Kniess, Torsten, Kluge, Michael, Beck-Sickinger, Annette G., Deuther-Conrad, Winnie, Krügel, Ute, Brust, Peter 03 January 2024 (has links)
The ghrelin receptor (GhrR) is a widely investigated target in several diseases. However, the current knowledge of its role and distribution in the brain is limited. Recently, the small and non-peptidic compound (S)-6-(4-bromo-2-fluorophenoxy)-3-((1-isopropylpiperidin-3-yl)methyl)-2-methylpyrido[3,2-d]pyrimidin-4(3H)-one ((S)-9) has been described as a GhrR ligand with high binding affinity. Here, we describe the synthesis of fluorinated derivatives, the in vitro evaluation of their potency as partial agonists and selectivity at GhrRs, and their physicochemical properties. These results identified compounds (S)-9, (R)-9, and (S)-16 as suitable parent molecules for 18F-labeled positron emission tomography (PET) radiotracers to enable future investigation of GhrR in the brain.
300

Synthesis of Highly Fluorinated Diels-Alder Polyphenylenes

Evans, Jessica 27 August 2010 (has links)
Fluoropolymers have useful properties including high thermal stability, chemical resistance, low dielectric constants, and both hydrophobic and oleophobic character, as compared to non-fluorinated analogues. Meanwhile, Diels-Alder polyphenylenes (DAPPs) are known for thermal stability as well as their rigid structure and glassy physical characteristics, which have led to a variety of film and membrane applications. This dissertation merges these two fields by demonstrating a novel and general synthetic approach to highly fluorinated DAPPs. These polymers are expected to retain the physical characteristics of glassy, non-fluorinated DAPPs while also incorporating the desirable attributes of fluoropolymers. The polymer synthesis described herein is based on the well-established polycondensation of bis(cyclopentadienone) (CPD) monomers and dialkynes. Our first main scientific contribution is a general method for preparing CPDs containing both a fluoroaromatic linker and variable fluoroaromatic head-groups. Our CPD synthesis uses nucleophilic aromatic substitution reactions of cyclopentadienyl anions and perfluoroarenes, as well as a new catalytic method of converting cyclopentadiene methylene (CH₂) groups into the corresponding ketones (C=O) that is the primary dissertation subject of Brian S. Hickory in our laboratory. The overall synthesis is notable for its use of inexpensive starting materials, its efficiency, and its structural versatility. Our second main contribution is the synthesis of novel highly fluorinated Diels-Alder polyphenylenes (DAPPs). Fluorinated DAPPs varied in their molecular weight, in the identity of the lateral fluoroaryl substituent (pentafluoro-phenyl or tetrafluoro-4-pyridyl), and in the structure of the aromatic dialkyne monomer. These polymers are glassy materials with high glass transition temperatures and high thermal stability. Since the polyphenylene structure is intrinsically rigid, the polymers form brittle films even at molecular weights of over 30,000 (M<sub>w</sub>). Unlike many fluoropolymers, the fluorinated DAPPs are freely soluble in common organic solvents such as tetrahydrofuran and chloroform. An unknown side reaction competes with the polymer propagation and reduces the highest obtainable molecular weights, which limit the ability to form films. However, a stoichiometric imbalance leads to highly fluorinated polyphenylene oligomers terminated with either alkyne or CPD end groups (M<sub>n</sub> = 9000). Because preliminary experiments had shown that the desired Diels-Alder propagation reaction was slower than expected, we also undertook a detailed model study of the reaction conditions needed for Diels-Alder reactions of fluorinated CPDs and aromatic alkynes. These experiments showed that protic polar solvents (e.g., m-cresol) and conventional heating at ca. 150 °C optimize reaction rate while minimizing side-reactions that can contribute to lower molecular weight in corresponding polymerization reactions. / Ph. D.

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