No description available.

In this report a novel low temperature synthesis approach of CdS nanocrystals is described starting from well known precursors, Cd(SA) and TOP-S, in a ligand system of aliphatic long chain alcohols. A one-pot synthesis approach is applied using a laboratory microwave heating source. The resulting CdS nanocrystals exhibit an absorbance with a pronounced fine-structure, a photoluminescence with a very high ratio between the band gap peak and the defect peak and a fluorescence quantum yield of 33%. Different synthesis approaches have been investigated by changing heating rate, temperature, precursor concentration and chain length of the aliphatic alcohol ligand as well as chain length of the Cadmium precursor. It was found that small changes in the heating rate do not affect the reaction. Changing the reaction temperature between 200°C and 160°C has no visible effects on the quality of the resulting CdS nanocrystals. At 140°C the nanoparticles experience a significant drop in quality, probably because there is a major change in the growth mechanism of the nanocrystals at that low temperature. At 100°C and 120°C the creation of so-called CdS nanoclusters is observed, and a growth mechanism towards nanocrystals based on cluster aggregation is suggested. For the synthesis of high quality nanoparticles it was found that a ratio of 1:25 between precursor and aliphatic alcohol is preferable as well as a ratio of 1:1 between the two precursors. If the chain length of both the precursors and the alcohol is short, the reaction rate is enhanced. If the chain length is too short the nanocrystals grow very fast and the size distribution gets broad, the photoluminescence intensity decreases and the ratio between band gap luminescence and defect luminescence decreases. The best Cd-precursor was found to be Cd-Laurate and the most suitable ligand evaluated was Tetradecanol.

The first section of this dissertation (Chapter I-III) describes the development of new methodologies to prepare uracil and arylidenehydantoin derivatives. A regioselective synthesis of 6-alkyl- and 6-aryluracils was developed by the dimerization of 3-alkyl- and 3-aryl-2-propynamides promoted by either Cs2CO3 or K3PO4. A range of 3-aryl-2- propynamides, with both electron-deficient and electron-rich 3-aryl substituents, were successfully reacted in high yields. A synthetic route to prepare arylidenehydantoins was developed using the Pd-catalyzed dimerization of 3-aryl-2-propynamides. Both electron rich and electron deficient 3-aryl-2-propynamides were dimerized successfully to produce the desired arylidenehydantoins in moderate to excellent yields. The second section of this dissertation (Chapter IV and V) describes the development of a reliable low-cost method to determine amounts of xylitol in sugar free gum samples to predict dangerous exposure levels for dogs. Xylitol is generally considered safe for human consumption and is frequently used in sugar free gum, however, it is extremely toxic to dogs. It is unknown if partially consumed chewing gum is also dangerous. A method to determine xylitol content of these sugar free gum samples employing GC-MS with direct aqueous injection (DAI) is presented. This method was successfully applied to over 120 samples including, fresh gum, 5 min, 15 min, and 30 min chewed gum samples. Further extension of this work resulted in the development of an undergraduate laboratory experiment for upper-level undergraduate chemistry students which teaches calibration methods, xylitol extraction, sample preparation for GC-MS analysis, and data analysis.

La méthodologie MAC consiste à employer des réactifs umpolung pour permettre l’insertion formelle d’une fonction carbonyle entre un électrophile et un nucléophile. Cette thèse est consacrée à l’oxyhomologation diastéréosélective de la L-sérine grâce à un développement significatif de la méthodologie MAC à trois composants en one-pot, conduisant à l’obtention de dérivés orthogonalement protégés de l’acide α, γ-dihydroxy-β-aminobutyrique. Ce dernier est une brique moléculaire acyclique à 4 atomes de carbone hautement fonctionnalisée qui est souvent intégrée dans les squelettes de molécules biologiquement actives.Nous avons tout d’abord étudié la synthèse de réactifs MAC silylés à partir du malononitrile. La synthèse du H-MAC-TBS a été optimisée et deux nouveaux réactifs MAC silylés, le H-MAC-TES et le H-MAC-TBDPS, ont été préparés.Dans un premier temps, nous avons étudié l’oxyhomologation du N-Boc-O-Bn-L-sérinal avec le H-MAC-TBS en présence de différents alcools dans des conditions réactionnelles douces. En présence de méthanol, des α, γ-dihydroxy-β-aminobutanoates de méthyle orthogonalement protégés ont été préparés avec des bons rendements et avec un ratio diastéréoisomérique syn/anti = 80/20.L’utilisation du H-MAC-TBDPS a permis d’améliorer la diastéréosélectivité de la réaction MAC (syn/anti = 90/10). L’étude des différents modes de cyclisation des α, γ-dihydroxy-β-aminobutanoates de méthyle a été réalisée par la suite. Des hétérocycles fonctionnalisés à 3, 5 et 6 chaînons ont été ainsi sélectivement synthétisés.De nouvelles oxazolidinones et oxazolines hautement fonctionnalisées ont été préparées de cette façon. En revanche, malgré nos efforts approfondis, une cyclisation pour donner un hétérocycle à 4 chaînons n’a pas été réalisée.L’absence de réactivité de la fonction alcool libre en α de ces esters N-protégés et γ activés a été inattendue.Dans un deuxième temps, nous avons étudié l’oxyhomologation de l’aldéhyde de Garner, un dérivé cyclique N,O-protégé du L-sérinal, par des réactions MAC. En présence de divers nucléophiles, cette réaction a conduit diastéréosélectivement à des esters et des amides protégés de l’acide α, γ-dihydroxy-β-aminobutyrique avec des bons rendements et avec une diastéréoselectivité anti, allant jusqu’à un ratio diastéréoisomérique syn/anti = 10/90 en utilisant le H-MAC-TBDPS. Il s’agit des premiers exemples de diastéréosélectivité antiobservée pour une réaction MAC. Des hétérocycles fonctionnalisés à 3 et 5 chaînons ont été sélectivement synthétisés et, grâce à une oxydation sélective en position γ, des dérivés de l’acide érythro-β-hydroxyaspartique et de l’érythro-β-hydroxyasparagine orthogonalement protégés ont été préparés. / MAC methodology is a synthetic technique which employs an umpolung reagent to formally insert a carbonyl function between an electrophile and a nucleophile. This thesis is devoted to the diastereoselective oxyhomologation of L-serine thanks to a significant development of 3-component one pot MAC methodology, providing a synthesis of orthogonally-protected derivatives of α, γ-dihydroxy-β-aminobutyric acid. This latter is a highly functionalized, acyclic, 4-carbon molecular building block which is a constituent part of various biologically active molecules.The synthesis of silylated MAC reagents from malononitrile was first studied. H-MAC-TBS’s synthesis was optimized and two new silylated MAC reagents, H-MAC-TES and H-MACTBDPS,were prepared.In a first study, the oxyhomologation of N-Boc-O-Bn-L-serinal was examined using H-MACTBS and a panel of alcohols in mild conditions.Methyl esters of orthogonally-protected α, γ-dihydroxy-β-aminobutanoic acid were prepared in good yields and with a diastereoisomeric ratio syn/anti = 80/20. The use of H-MAC-TBDPS improved the diastereoselectivity of the MAC reaction to syn/anti = 90/10.Subsequently, different cyclization modes of methyl α, γ-dihydroxy-β-aminobutanoate were investigated, leading to the selective synthesis of functionalized 3-, 5- and 6-membered ring heterocycles, including new highly functionalized oxazolidinones et oxazolines. In contrast, despite considerable efforts, we were unable to induce cyclisation to forma a 4-membered ring heterocycle, due to the surprising lack of nucleophilicity of the free alcohol function in the acyclic precursors.In a second study, we examined the oxyhomologation of Garners aldehyde, a cyclicN,O-protected derivative of L-serinal, using a selection of nucleophiles via one-pot MAC methodology. These reactions furnished protected ester and amide derivatives of α, γ-dihydroxy-β-aminobutyric acid in good yields with an anti diastereoselectivity with a ratio as high as syn/anti = 10/90 when H-MAC-TBDPS was used as the MAC reagent. These are the first known examples of MAC reactions which proceed with anti diastereoselectivity.Functionalized 3- and 5-membered ring heterocycles were prepared from these adducts,and via selective oxidation at the γ-position,orthogonally-protected derivatives of erythro-β-hydroxyaspartic acid and erythro-β-hydroxyasparagine were prepared.

No description available.

Les ions phosphiraniums sont connus depuis plus d’une cinquantaine d’année mais leur ouverture C-centrée n’a jamais été décrite. Une telle réactivité permettrait d’obtenir des phosphines β fonctionnalisées de façon innovante ouvrant ainsi la voie à de nouvelles perspectives synthétiques. De nouveaux phosphiranes ainsi que les ions phosphiraniums correspondant ont été synthétisés au travers de réactions innovantes d’alkylations et d’arylations. Ces composés ont par la suite pus être ouverts sélectivement sur le carbone du cycle pour la première fois, ce par l’intermédiaires de différents nucléophiles azotés. La méthodologie proposée au cours de ce projet de thèse a permis l’obtention de composés de type β-aminophosphines innovants tant par la structure que par la voie d’accès. De nombreux paramètres ont pu être étudiés pendant cette étude afin de mieux appréhender les différentes interactions et facteurs régissant cette réactivité singulière. / Phosphiraniums ions are known for more than fifty years. However, heir C-centered ring opening has never been reported. This novel reactivity would grant access to β-functionalized phosphines in an innovative manner, opening the way to new synthetic perspectives. Novel phosphiranes as well as their corresponding phosphiraniums have been synthesized through alkylation and arylation reactions. Then, these compounds were reacted with different nitrogen compounds allowing their ring opening in a C-centered fashion for the very first time. New β-aminophosphines could be accessed this way in regards for their innovative structure and synthetic pathway. Various parameters have been studied to increase our understanding on these specific yet promising reactions.In this line, along this PhD project, interactions and factors which might rule this particular reactivity were screemed.

Les synthèses « one pot » multi-étapes efficaces et éco-compatibles ont été envisagées pour la synthèse de molécules potentiellement bioactives tels que les systèmes bis(bibenzyliques) et leurs précurseurs stilbéniques ou bibenzyliques par catalyse hétérogène au palladium. Une synthèse « one-pot » impliquant une réaction de couplage de Heck suivie d’une hydrogénation des stilbènes ainsi formés a été mise au point en présence de Pd/C. Cette stratégie c’est révélée être limitée lors de l’application à des substrats désactivés et stériquement encombrées. Couplée au manque de disponibilité commerciale d’oléfines aromatiques intéressantes pour nos objectifs, nous avons mis au point une synthèse de styrènes par catalyse hétérogène à partir d’halogénures d’aryles et du vinyltrifluoroborate de potassium impliquant un couplage de Suzuki-Miyaura. Cette vinylation hétérogène a été ensuite appliquée à la synthèse « one-pot » de stilbènes. Des études d’optimisation de ce procédé sont encore en cours. Les stilbènes ainsi obtenus ont été utilisée pour la synthèse de bis(bibenzyles) ouverts et fermés. Pour ce faire différentes stratégies « one-pot » ont été évaluées au cours de ces travaux et des bis(stilbènes) ont été obtenus avec des rendements compris entre 30% et 50%. Les bis(stilbènes) ainsi obtenus ont été l’objet d’études en hydrogénation. A ce jour aucune de nos tentatives n’a permis l’obtention de bis(bibenzyles) quelles que soient les conditions employées. Des études sont en cours pour comprendre les raisons de ces résultats et obtenir les bis(bibenzyles) cibles de nos travaux / “One-pot” strategy, powerful tools for the creation of molecular complexity, has been applied in the synthesis of possible bioactive molecules such bis(bibenzyls) systems and their precursors stilbenes and bibenzyles using heterogeneous palladium catalysts. In this work a “one-pot” synthesis concerning a Heck coupling reaction followed by in situ hydrogenation with Pd/C has been studied for the synthesis of bibenzyl derivates. We have observed limitations for deactivated and hindered substrates. Moreover due to the low commercially availability of aromatic styrenes we focused our attention on the development of new heterogeneous vinylation reaction starting from aromatic halides and potassium vinyltrifluoroborate through a Suzuki coupling reaction. This strategy was then applied to “one-pot” stilbenes synthesis. The study is still under investigation in our laboratory. The synthesized stilbenes have been used as precursors in the synthesis of cyclic or acyclic bis(bibenzyls) derivates. Many different “one-pot” strategies have been developed that allowed to reach yields of bis(stilbenes) between 30% and 50% in only one step. Bis(stilbenes) have been objects of investigation as what concerned the hydrogenation. However every effort has not yet been successful under our reaction conditions. Studies are still in progress to understand the reasons of these results and to obtain bis(bibenzyls) systems, target of our research

Le développement d’une chimie propre et donc durable est un des challenges majeurs du 21ème siècle dans les pays industrialisés. Étant au cœur de nombreuses découvertes dans divers domaines scientifiques allant de la physique à la médecine, les sciences chimiques doivent jouer un rôle central pour résoudre un certain nombre de problèmes environnementaux auxquels nous devons faire face. Mon travail de thèse s’inscrit dans cette problématique par le développement de méthodologies de synthèse faisant intervenir plusieurs transformations dans le même réacteur. Nous avons notamment développé des séquences réactionnelles appelées HRC (pour Heck-Reduction-Cyclization, en anglais) prenant appui sur le caractère multi-tâche d’un catalyseur à base de palladium. Ces travaux nous ont permis de préparer une grande variété d’hétérocyles ou composés fonctionnalisés parmi lesquels nous pouvons citer les oxindoles, les indanones, ou encore les naphthoxindoles. Ces travaux ont donné lieu pour le moment à quatre publications dans des journaux à comité de lecture. / The development of clean chemistry and therefore sustainable is one of the major challenges of the 21st century in industrialized countries. Being in the heart of many discoveries in various scientific fields ranging from physics to medicine, the chemical sciences must play a central role in solving a number of environmental problems we face. My thesis work is part of this problem through the development of synthetic methodologies involving several transformations in the same reactor. We have developed the reaction sequences called HRC (for Heck-Reduction-cyclization) building on the multi-task of a palladium catalyst. This work allowed us to prepare a variety of functionalized heterocycles or compounds from which we can cite the oxindole, the indanones, or the naphthoxindoles. This work has resulted for the time four publications in peer-reviewed journals.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The present work describes a methodology of controlled synthesis of block copolymers by one-pot reactions involving simultaneous RAFT and ROP processes mediated by a bifunctional compound which acts as a chain transfer agent (CTA) for the RAFT process and co-initiator of the ROP process. Reactions involving the RAFT of Styrene (St) and the ROP of ε-Caprolactone (ε-CL) were performed to obtain PS-b-PCL diblock copolymers. The catalysts Sn(Oct)2 and diphenyl phosphate (DPP) were evaluated in the ROP process. Diphenyl phosphate is the most appropriate for this kind of reaction, since Sn(Oct)2 proved to be avid when interacted with CTA, interfering antagonistically in the radical equilibrium of the RAFT process. The reactions were always controlled when DPP was used as a ROP catalyst, wherein copolymers with narrow molar mass distribution were obtained in the end. This methodology was employed in the synthesis of other linear and graft amphiphilic block copolymers, proving to be an excellent alternative for this purpose. Thermoresponsive copolymers based on Poly(oligo(ethylene glycol)methyl ether methacrylate) (POEGMA) and pH responsive based on Poly(acrylic acid) (PAA) were obtained. The physicochemical properties of the copolymers were investigated in solid state as well as in solution, and the results are in total agreement with values reported in the literature. / Este trabalho descreve uma metodologia de síntese controlada de copolímeros em bloco por reações one-pot envolvendo processos RAFT e ROP simultâneos, mediados por um composto bifuncional que atua como agente de transferência de cadeia (CTA) para o processo RAFT e co-iniciador do processo ROP. Reações envolvendo a RAFT do estireno (St) e a ROP da ε-Caprolactona (ε-CL) foram realizadas para obter copolímeros dibloco PS-b-PCL. Os catalisadores Sn(Oct)2 e difenil fosfato (DPP) foram avaliados, sendo o último o mais apropriado para este tipo de reação, uma vez que Sn(Oct)2 mostrou-se ávido por interações com o CTA, interferindo antagonicamente no equilíbrio de radicais do processo RAFT. As reações mantiveram o caráter controlado quando DPP foi usado como catalisador ROP, sendo que ao final, copolímeros com estreita distribuição de massa molar foram obtidos. Esta metodologia foi empregada na síntese de outros copolímeros em bloco anfifílicos lineares e enxertados, se mostrando uma excelente alternativa para este propósito. Copolímeros termoresponsivos à base de Poli(metacrilato de poli(etilenoglicol)metil éter) (POEGMA) e pH responsivos à base de Poli(ácido acrílico) (PAA) foram obtidos. As propriedades físico-químicas dos copolímeros foram investigadas em estado sólido e em solução, e os resultados estão em plena concordância com valores relatados na literatura.

The goal of this study is to present kinetic studies of (co)polymerization as well as the synthesis and characterization of amphiphilic copolymers with a fluorinated segment. Copolymers were obtained by RAFT (co)polymerizations using one-pot and miniemulsion methods. Different monomers were used to obtain stable selforganized systems, being that one of them was always fluorinated. The resulting copolymers showed different properties, especially when evaluating their selforganization. For this reason, different methodologies for self-organization were used, depending on the synthetic route by which the copolymers were obtained. The self-organization systems formed by the fluorinated amphiphilic copolymers were analyzed by dynamic light scattering (DLS) to determine the size and distribution of the species. The micellar systems analyzed showed great potential for the use in diagnostic imaging, which makes it possible to identify the presence of fluorine in the interior of the micelles through 19F NMR analysis. Relaxation times T1 were measured and values were similar to those reported in the literature. To reinforce the above statement, we performed cell viability assays, which demonstrated the biocompatibility of fluorinated amphiphilic copolymers. / O objetivo deste trabalho é apresentar estudos cinéticos de (co)polimerizações bem como a síntese e a caracterização de copolímeros anfifílicos contendo um segmento fluorado, os quais foram obtidos através de (co)polimerizações RAFT pelos métodos one-pot e miniemulsão. Diferentes monômeros foram utilizados para a obtenção de sistemas auto-organizados estáveis, sendo um deles sempre fluorado. Os copolímeros resultantes apresentaram propriedades distintas, principalmente quando se avalia a autoorganização dos mesmos. Por este motivo, diferentes metodologias para autoorganização foram utilizadas, dependendo da rota sintética pela qual os copolímeros foram obtidos. Os sistemas auto-organizados formados pelos copolímeros anfifílicos fluorados foram analisadas por espalhamento de luz dinâmico (DLS) para determinação de tamanho e distribuição das espécies. Os sistemas micelares analisados apresentaram grande potencial para utilização em diagnósticos por imagens sendo possível identificar a presença de flúor no interior das micelas através de análises por RMN 19F. Os tempos de relaxação T1 foram medidos e os valores encontrados foram semelhantes aos reportados na literatura. Para reforçar a afirmação acima, foram realizados ensaios de viabilidade celular que demonstraram a biocompatibilidade dos copolímeros anfifílicos fluorados.