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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.
141

Design of New Polyester Architectures through Copolymerization, Crosslinking, and Diels-Alder Grafting

Vargas, Marian 12 April 2004 (has links)
The compound 2,6-anthracenedicarboxylic acid is used as a comonomer for the synthesis of poly(ethylene terephthalate). The resulting copolymers are characterized and further functionalized by Diels-Alder grafting or crosslinking through the anthracenate unit. Diels-Alder reaction is used to graft small molecules and oligomers endcapped with maleimide as dienophiles on to poly(ethylene terephthalate-co-2,6-anthracenedicarboxylate),PET-co-A. Maleimide-capped poly(ethylene glycol) is grafted onto PET-co-A to improved its hydrophilicity. 2,6-Anthracenedicarboxylic acid is also incorporated into the known liquid crystalline polymer, LCP, poly(4-oxybenzoate-co-1,4-phenylene isophthalate), HIQ40. The resulting copolymer, poly(4-oxybenzoate-co-1,4-phenylene isophthalate-co-2,6-phenylene anthracenate), HIQ40-co-A, shows LCP behavior. These HIQ40-co-A copolymers are grafted with maleimide end-capped monomers and polymers andcrosslinked with bismaleimides through a Diels-Alder mechanism.
142

Estudos sobre a síntese de furanoeliangolidos a partir da reação de Diels-Alder / Studies about synthesis of furanoheliangolies from Diels-Alder reaction

Susimaire Pedersoli 06 February 2006 (has links)
O objetivo deste trabalho foi iniciar o estudo de uma nova metodologia sintética para a obtenção do sistema 11-oxabiciclo[6.2.1]undecano, o esqueleto estrutural básico de uma classe de produtos naturais conhecidos como furanoeliangolidos. A abordagem sintética proposta envolveria a formação de um composto bicíclico através da reação de Diels-Alder com derivados de furano, seguida pela formação de um hexanel e, finalmente, ruptura de uma ligação central para formação do sistema macrocíclico. Além disso, a reação de Diels-Alder entre derivados de furano e acetileno dará origem a compostos que apresentam como esqueleto estrutural o sistema 7-oxabiciclo[2.2.1]heptano, que podem ser utilizados como material de partida para a síntese de diversos produtos naturais. Iniciamos este estudo com a reação de Diels-Alder entre o 3,4-dimetoxi-2-metil furano e o bromopropiolato de metila, onde foi obtido o produto 85, que após algumas modificações deu origem ao composto 92. Entretanto, após inúmeras tentativas não conseguimos transformar o composto 92 no triciclo desejado. Para evitar essas transformações que se mostraram problemáticas, resolvemos estudar a reação de Diels-Alder entre derivados de furano e benzoquinonas 2,5-dissubstituídas, que dará origem aos adutos devidamente funcionalizados para serem transformados no derivado do sistema 11-oxabiciclo [6.2.1]undecano. No entanto, após o estudo dessas reações de cicloadição, observamos que elas têm o equilíbrio fortemente deslocado no sentido dos materiais de partida. Por esse motivo, a continuidade desta metodologia sintética mostrou ser inviável. Iniciamos então, um estudo da reação de Diels-Alder entre os diverso derivados de furanos e acetilenos. Após o estudo dessas reações de Diels-Alder foi possível verificar que a maioria dos adutos derivados dos furanos é instável no meio reacional. Os melhores resultados obtidos nessas reações de Diels-Alder foram usando o acetilenodicarboxilato de dimetila como dienófilo. Os adutos obtidos são intermediários importantes e bem funcionalizados, que podem ser utilizados na continuidade do estudo de desenvolvimento de nova metodologia sintética para a obtenção do sistema 11-oxabiciclo[6.2.1]undecano / The aim of this work was to start the study of a new methodology to synthesize the 11-oxabicycle[6.2.1]undecane system, the main carbon skeleton of the furanoheliangolides. The proposed synthetic approach involves the preparation of a bicyclic compound through a Diels-Alder reaction with furan derivatives, followed by formation of a six membered ring and, finally, cleavage of the central bond to obtain of the macrocyclic system. The Diels-Alder reaction between furan and acetylene derivatives gives a compound with the 7-oxabicyclico[2.2.1]heptane system, that is a potential starting material for the synthesis of several natural products. We started this study with the Diels-Alder reaction between the 3,4-dimethoxy-2-methylfuran and methyl bromopropiolate, and obtained the product 85 that after some modifications furnished the compound 92. However, after various attempts we were unable to convert the compound 92 into the desired tricycle. We have then decided to study the Diels-Alder reaction between furan and 2,5-disubstituted benzoquinone derivatives, that could furnish the adducts properly functionalized to be transformed in the 11-oxabicyclico[6.2.1]undecane system. However, we observed that the equilibrium is strongly shifted towards the starting materials in these cycloaddition reactions. This methodology has thus showed to be impracticable. As a third alternative, we affected the study the Diels-Alder reaction between the furans derivatives and the acetylenes. The adducts obtained present 7-oxabicyclico[2.2.1]heptane system that could be used to synthesizes of structural skeleton of furanoheliangolide.
143

Derivados porfirínicos com potencial aplicação em terapia fotodinâmica. Alterações estruturais / Porphyrinic Derivatives with Potential Application in Photodynamic Therapy. Structural Modifications.

Vinícius Silveira Garcia 13 March 2008 (has links)
Devido à sua intensa absorção de luz na região visível do espectro, as porfirinas e seus derivados (clorinas e bacterioclorinas) são de grande importância na terapia fotodinâmica (TFD) para o tratamento de doenças neoplásicas. Neste trabalho foram sintetizadas as novas vinil-porfirinas estrategicamente funcionalizadas (47 e 48), seguida de uma sistemática de reações de Diels-Alder com dieófilos ativados, com o propósito de obter clorinas e/ou bacterioclorinas para potenciais aplicações em TFD. / Due to their strong absorption in the visible region, porphyrins and related derivatives (chlorins and bacteriochlorins) are very important in photodynamic therapy (PDT) for the treatment of neoplasic diseases. In this work were synthesized the novel and strategically functionalizated vinyl-porphyrins 47 and 48, followed by systematic Diels-Alder reactions with activated dienophiles to obtain chlorins and/or bacteriochlorins, potentially useful on PDT.
144

Syntheses and the Structures of Polymethylpolycyclic and Polycyclic "Cage" Molecules

Zhao, Dalian 05 1900 (has links)
The structures of Diels-Alder cycloaddition of cyclopentadiene to 2,6-dimethyl-p-benzoquinone and methylcyclopentadiene to 2,6-dimethyl-p-benzoquinone were assigned by analysis of 1-D and 2-D proton and carbon-13 NMR spectra. The structures of the cycloadduct of methylcyclopentadiene to 2,6-dimethyl-p-benzoquinone and that of the corresponding intramolecular [2+2] photocyclization product were also obtained by single crystal X-ray structural analysis. As the second part of the study, a new polycyclic "cage" molecule, a substituted trishomocubane isomer, was synthesized. In this synthesis, reductive bond cleavage followed by Dieckmann condensation was employed. Wolff-Kishner reduction then was used to convert a β-keto ester "cage" molecule to the corresponding carboxylic acid. A compound that possesses twofold symmetry was isolated from reaction product mixture. The structure of this compound has been established by single crystal X-ray crystallography.
145

Synthèse de tropyliums fonctionnalisés et de quinoxalines à partie d'électrophiles fluorés / Synthesis of fonctionalised tropyliums and quinoxalines from fluorinated electrophiles

Jovene, Cyril 09 June 2015 (has links)
Les benzofuroxanes sont des hétérocycles possédant des propriétés biologiques importantes. Ce type de composés possède une forte électrophilie en fonction du nombre de groupements électroattracteurs présent sur leur carbocycle. Les travaux de recherche de cette thèse s’inscrivent dans la continuité des travaux reportés dans ce domaine. Ainsi, dans une première partie purement bibliographique, sera développé l’historique de la synthèse et de la réactivité des benzofuroxanes ainsi que les travaux du laboratoire.Dans une seconde partie est présenté le développement de voies de synthèses originales vers des fluoronitrobenzofuroxanes à partir de composés simples et variés de type phénols, anisoles, et anilines. La synthèse de composés benzofuroxanes polyfluorés est ensuite présentée, revisitant la formation du 4,6-difluorobenzofuroxane qui a permis de mettre en évidence des résultats erronés de la littérature et de proposer une nouvelle méthode efficace pour sa formation. L’utilisation de la RMN à température variable a permis de déterminer sans ambiguïtés la structure de ces benzofuroxanes fluorés.Dans une troisième partie, leur réactivité est étudiée selon plusieurs méthodes, de la réactivité péricyclique à des calculs théoriques d’électrophilie globale en passant par des potentiels de réduction mesurés par voie électrochimique. Ces résultats sont comparés à d’autres électrophiles comme le trinitrobenzène en série aromatique ou le DNBF, pour les molécules superélectrophiles. De plus, la formation de quinoxalines possédant potentiellement des activités biologiques sera décrite.Dans une quatrième partie, la synthèse de composés de type benzodifuroxanes est développée. Après une introduction sur leurs caractéristiques structurales, la synthèse du 4-fluorobenzodifuroxane est décrite ainsi que la formation des analogues bromé et iodé. D’autre part la synthèse du 4-méthoxybenzodifuroxane et du 4-aminobenzodifuroxane sera décrite permettant d’apporter des informations sur la réactivité de ce type de composés.Enfin dans un dernier chapitre, la réactivité d’un électrophile chargé tel que le tropylium vis-à-vis de nucléophiles faibles indoliques sera présentée. La réaction de couplage avec le tropylium permettra de mettre en valeur la régiosélectivité de ce couplage. Les tropylidènes obtenus seront caractérisés afin de mettre en avant les caractéristiques spectrales de ce type d’adduit. Les tropylidènes formés sont ensuite oxydés afin de conduire à des tropyliums fonctionnalisés très colorés qui peuvent être aussi obtenus en une seule étape.Finalement, cette thèse s’achèvera sur une conclusion générale qui présentera aussi les perspectives sur le sujet et ce que ces travaux ont apporté à la chimie des benzofuroxanes. / Benzofuroxans are heterocycles exhibiting many biological activities. This kind of compounds has been shown to be very electrophilic spieces when substituted by electron-withdrawing groups. This work is an important part of the works reported in this field of heterocyclic chemistry. In the first part of this PhD thesis, one will find the bibliographic part dedicated to benzofuroxans including the works of our team.In a second part, the development of original synthetic pathways leading to fluoronitrobenzofuroxans from simple compounds like phenols, anisoles or anilines is shown. The synthesis of polyfluorinated benzofuroxans will be presented by revisiting the formation of 4,6-difluorobenzofuroxan highlighting erroneous published results and allowing the finding of new and efficient methods leading to the difluorinated benzofuroxan. The use of variable temperature NMR experiments allows the unambiguous determination of the structure of fluorinated benzofuroxans.In a third part the reactivity of benzofuroxans is studied using different methods such as the experimental study of the pericyclic Diels-Alder reaction, theoretical calculations of global electrophilcity and the electrochemical measurements of reduction potentials. These results are compared to those of other electrophiles like trinitrobenzene in the usual aromatic series and of 4,6-dinitrobenzofuroxan in the superelectrophilic dimension. Then, the formation of quinoxalines exhibiting potential biological activities will be described.In a fourth part the synthesis of benzodifuroxan-type compounds is developed. After an introduction dealing with their main structural features, the synthesis of the 4-fluorobenzodifuroxan and the formation of brominated and iodinated analogs are described. Then the synthesis of the 4-methoxybenzodifuroxan and the 4-aminobenzodifuroxan will bring interesting informations on the reactivity of this kind of compounds.In a last chapter the reactivity of the tropylium cation with weak nucleophiles such as indoles will be presented. The C-C coupling reactions with the tropylium cation allow the isolation of many tropylidenes moieties, which will be subsequently oxidized to lead to highly functionalized and colored substituted tropyliums.Finally, a general conclusion will summarize the significant results and the perspectives of this work in the field of benzofuroxans chemistry
146

Novel applications of polyfunctionalised organoboron and nitroso compounds / Composés organoborylés polyfonctionnalisés et dérivés nitroso : nouvelles applications

Eberlin, Ludovic 15 January 2016 (has links)
Cette thèse présente la réactivité de diènes polyfonctionnalisés incorporant un atome de bore (diènes borylés) en présence de composés de type nitroso. La première partie est une étude de la réactivité des diènes borylés en présence de dérivés arylnitroso. Le produit formé ainsi que l'efficacité de la réaction est dépendant de la substitution sur l'atome de bore ainsi que du solvant utilisé pour la réaction. Suivant les conditions employées, la formation de composés avec différentes structures; pyrroles, oxazines substitués par un atome de bore, ou nitrones a été obtenue. Une stratégie one-pot a ensuite été développée pour la synthèse d'oxazolines utilisant la formation des nitrones en tant qu'intermédiaire. Des investigations théoriques et pratiques concernant le mécanisme de la formation du pyrrole ont été réalisées. La séquence expliquant la synthèse de cette structure est basée sur la cascade suivante; cycloaddition régiosélective (Nitroso Diels-Alder)/réarrangement/élimination du borate. La formation des composés de type nitrone n'a pas été totalement explicité. Des recherches sont actuellement en cours dans le but d'obtenir plus de détails sur le mécanisme mis en jeu. La deuxième partie de l'étude est orientée sur la réactivité des diènes borylés en présence de dérivés carbonylnitroso. Au contraire des dérivés arylnitroso, la nature du composé carbonylnitroso joue un rôle majeur sur la réactivité. Si le même type de réactivité engendrant la formation de pyrroles et d'oxazines substitués par un atome de bore a été observé dans certains cas, l'utilisation d'un composé carbonylnitroso étant assez pauvre en électrons génère la formation du produit issu d'une réaction nitroso-ène. Ce produit, issu de la réaction nitrosoène, a été utilisé comme intermédiaire clé pour la synthèse de différents produits polycycliques. Une séquence one-pot, multicomposants, Diels-Alder/allylboration a été optimisée donnant différentes structures suivant le dienophile et l'aldehyde employé. Dans le but de diversifier la chimie du produit résultant de la réaction nitroso-ène, une autre séquence a été mise au point utilisant la synthèse des pyrroles. Une voie multi-étape a permis la synthèse de nouvelles structures bicycliques incorporant une oxazine et un pyrrole. / This thesis presents the reactivity of dienylboronated compounds towards arylnitroso and carbonylnitroso derivatives and its use in the synthesis of heterocyclic and polycyclics compounds. The first study focused on the reactivity of dienylboronate compounds with arylnitroso derivatives resulting in pyrrole or furan products. The outcome and efficiency of the reaction is related to the boron on the dienyl moiety and the solvent used. Using the certain conditions, pyrroles, boronated MIDA ester oxazines or nitrones could be obtained. A one-pot strategy was then applied to synthesise oxazoline derivatives using nitrones as an intermediate. Theoretical, as well as experimental, work has supported that the formation of the pyrrole was obtained by a regioselective nitroso Diels-Alder reaction/rearrangement/borate elimination cascade process. Details on the nitrone formation have not been clarified, but further investigations are on-going. Secondly, attention was focused on the reactivity of dienylboronate compounds with carbonylnitroso derivatives. Contrary to the arylnitroso species, the nature of the carbonylnitroso had a dramatic impact on reactivity. On the one hand, similar reactivity towards the formation of pyrroles and boronated MIDA ester oxazines was observed, however, by employing a higher electron-deficient carbonylnitroso species, the product resulting from a nitroso-ene reaction was obtained. Ene-product was used as the key intermediate for the synthesis of different polycyclic compounds. A multicomponent, one-pot, Diels-Alder/allylboration procedure was optimised to yield various structures depending on the nature of the dienophile and the aldehyde. To diversify the chemistry of the ene-product another sequence was designed using the pyrrole synthesis. A multi-step pathway was optimised to afford novel fused bicylic oxazine-pyrrole products.
147

Synthèse et caractérisations de réseaux thermosensibles à base époxy / amine par réactions de Diels-Alder / Epoxy-amine based thermoresponsive networks designed by Diels-Alder reactions

Marref, Mohamed 26 September 2013 (has links)
Les réactions de Diels-Alder (DA) sont connues pour leur thermo-réversibilité. A basse température, le diène et les fonctions réactives diénophiles réagissent ensemble par la réaction de (DA) pour donner l’adduit. Le but de notre thèse est d’élaborer des réseaux réticulés thermoréversibles à base époxy-amine en utilisant des réactions de Diels-Alder. La thèse est composée de cinq chapitres dont le premier est consacré à la partie bibliographique. Celle-ci résume une partie des travaux réalisés sur la synthèse d'adduits et expose les différentes conditions utilisées pour aboutir à la synthèse, ainsi que les différentes méthodes d’analyse pour la caractérisation de ces adduits. Le deuxième chapitre est consacré à la synthèse et caractérisations des pré-polymères multi-diéne furanne ester. La synthèse de ces pré-polymères a été réalisée et confirmée par la RMN-1H, avec l’apparition de nouveaux signaux entre 4 et 5 ppm prouvant l’estérification. L’analyse IR- TF confirme l’apparition des deux bandes de vibration correspondantes à la fonction ester. Le troisième chapitre est consacré à la synthèse et caractérisations des pré-polymères acides multi-diénophiles (diénophiles ouverts) et une tri-maléimide diénophile (diénophile fermé). Les analyses RMN-1H et IR-TF confirment, respectivement, la disparition des protons de la fonction amine et les deux bandes anhydride, avec ouverture de la fonction époxy. Le quatrième chapitre est consacré à la synthèse et caractérisations de pré-polymères multi-diène furane. Ceux-ci ont été réalisés par la réaction de copolymérisation entre les fonctions époxydes de la DGEBA et la phényl diglycidyl éther (PGE) avec la furfurylamine (FAM). La RMN-1H a permis de calculer la fonctionnalité en fonction furane des diènes et de déterminer leur masse molaire moyenne en nombre. L’analyse thermogravimétrie (ATG) et l’analyse thermique par DSC ont montré que ces diènes sont des composés amorphes présentant une Tg de l’ordre de 20°C et restent stables thermiquement jusqu'à une température de 230°C. Enfin, dans le cinquième et dernier chapitre, la synthèse de réseaux thermoréversibles formés par la réaction de Diels-Alder entre les pré-polymères diène et la tri-maléimide diénophile sera présentée. La thermoréversibilité, les propriétés thermiques et d’autoréparation des réseaux seront étudiées / The Diels-Alder (DA) reactions are known for their thermo-reversibility. At low temperatures, the diene and dienophile reactive functional groups react together by the reaction of (DA) to give the adduct. The aim of this thesis is to develop the thermo crosslinked networks based epoxy-amine using Diels-Alder reaction. The thesis consists of five chapters; the first is devoted to the bibliographic part. It summarizes some of the work on the synthesis of adducts and describes various conditions used to achieve the synthesis, and the different methods of analysis for the characterization of these adducts. The second chapter is devoted to the synthesis and characterization of multi-diene pre-polymers furan ester. The synthesis of these pre-polymers was carried out and confirmed by 1H-NMR, with the appearance of new signals between 4 and 5 ppm proving the esterification. FT-IR analysis confirmed the appearance of two bands corresponding to the ester vibration bands. The third chapter is devoted to the synthesis and characterization of pre-polymers multi-dienophiles acids (open dienophiles) and a tri-maleimide dienophile (dienophile closed). 1H-NMR analysis and FT-IR confirm respectively, the disappearance of the amine protons and two anhydride bands, with opening of the epoxy function. The fourth chapter is devoted to the synthesis and characterization of pre-polymers multi-furan diene. These were synthesized by the copolymerization reaction between the epoxy functions of DGEBA and diglycidyl phenyl ether (PGE) with furfurylamine (FAM). 1H-NMR was used to calculate the functionality dienes and to determine their number-average molar mass. The thermo gravimetric analysis (TGA) and the thermal analysis by DSC showed that these dienes are amorphous compounds having a Tg about 20°C and are thermally stable up to a temperature of 230°C. In the fifth and final chapter, the synthesis of thermo-reversible networks formed by the Diels-Alder reaction between pre-polymers diene and tri-maleimide dienophile will be presented. The thermoreversibility, thermal properties and self-healing networks are studied
148

Développement de ligations chimiosélectives "click" : applications à la synthèse de sondes fluorescentes / Development of chemoselective "click" ligations : application to the synthesis of fluorescent probes

Renault, Kévin 13 September 2018 (has links)
Depuis quelques décennies, l’étude de systèmes biologiques complexes est un domaine en plein essor. Ainsi, des outils de ligation des biomolécules avec des reporters chimiques ont été mis en place afin d’avoir une compréhension toujours fine du vivant. Les ligations sont des réactions chimiques biocompatibles permettant de lier deux entités synthétiques ou biologiques entre elles. On regroupe généralement ces ligations en deux catégories, les réactions de bioconjuguaison, qui font intervenir des fonctions chimiques naturellement présentes dans les biomolécules, et les réactions bio-orthogonales qui n’interfèrent pas avec les fonctions chimiques présentes dans ces milieux, mais nécessitent en amont une modification des partenaires de réaction. Cependant, il convient de faire la distinction avec une troisième catégorie, les réactions de conjugaison chimiosélectives, qui mettent en oeuvre des fonctions non naturellement présentes sur les biomolécules. En ce sens, elles se rapprochent donc des réactions bio-orthogonales, mais les fonctions ou conditions mises en jeu ne sont pas suffisamment bio-orthogonales ou les réactions ne sont pas suffisamment rapides pour pouvoir être réalisées dans les systèmes biologiques. Ces ligations sont toutefois très utilisées pour de la construction biomoléculaire allant de la petite molécule (par exemple oligopeptide modifié) à la biomacromolécule (type protéine modifiée) et se distinguent par une facilité de mise en oeuvre et purification des conjugués, ce qui n’est pas toujours réa lisable avec l’arsenal des réactions bio-orthogonales qui conduisent à la formation de multiple isomères. Ainsi, mes travaux de thèse se sont orientés vers la découverte et/ou l’étude de ligations chimiosélectives ainsi qu’à leur utilisation dans la préparation de sondes fluorescentes voire fluorogéniques. L’étude de la ligation Kondrat’eva préalablement développée au sein du laboratoire, a permis de mettre en évidence son caractère fluorogénique, et a été exploitée pour le marquage fluorescent de molécules via une étape unique de ligation fluorogénique. Puis, le développement d’une ligation utilisant le système tétrazine/pyrazolone a été développée afin de pallier le manque de sélectivité des réactions basées sur le motif tétrazine proposées jusqu’alors, qui conduisent aux bioconjugués sous la forme d’un mélange de produits. Cette approche a été illustrée par le marquage fluorescent d’une protéine humaine. Enfin, le développement d’une nouvelle voie d’accès aux quinoxalinones a permis leur étude photophysique et la mise en évidence de propriétés fluorogéniques utilisées notamment pour la synthèse d’une biosonde. / In recent decades, the study of complex biological systems has been a growing field. Thus, biomolecules ligation tools with chemical reporters were set up in order to have a better and fine understanding of the living. Ligations are biocompatible chemical reactions that link two synthetic or biological entities one antother. These ligations are generally gathered into two categories, bioconjugation reactions, using chemical functions naturally present in the biomolecules, and bio-orthogonal reactions which does not interfere with these function, but require a prior engineering of the biological partner. However, it is necessary to distinguish a third category, the chemoselective conjugation reactions, which implement functions not naturally present on biomolecules. In this sense, they are therefore closer to bio-orthogonal reactions, but the functions or conditions involved are not sufficiently bioorthogonal or the reactions are not fast enough to be carried out in any biological systems. These ligations are, however, widely used for biomolecular constructions ranging from the small molecule (for example modified oligopeptides) to the biomacromolecule (protein modification) and are distinguished by their ease of implementation and purification of the conjugates, which is not always feasible with the arsenal of bio-orthogonal reactions that leads to the formation of multiple isomers. Thus, my PhD work focused on the discovery and / or the study of chemoselective ligations as well as their use in the preparation of fluorescent or fluorogenic probes. The study of the Kondrat'eva ligation previously developed within the laboratory, highlighted its fluorogenic behaviour, and was exploited for the fluorescent labelling of molecules through a single fluorescence-ligation step. Then, the development of a ligation using the tetrazine / pyrazolone system was developed in order to overcome the lack of selectivity of the reactions based on the tetrazine scaffold which often lead to the formation of bioconjugates as a mixture of isomers. This approach has been illustrated by the fluorescent labelling of a human protein. Finally, the development of a new access route to quinoxalinones allowed to study their photophysical properties and to highlight their fluorogenic properties which were leveraged in particular for the synthesi s of a bioprobe.
149

I. DIELS-ALDER REACTIONS OF TRIMETHYL CYCLOPENTADIENYL STANNANE. II. PREPARATION AND DIELS-ALDER REACTIONS OF VINYLSULFOXIMINES.

REINEKE, KARL EDWARD, II. January 1983 (has links)
In Part 1, the Diels-Alder adducts of trimethyl cyclopentadienylstannane (I.3) with maleic anhydride and fumaronitrile are prepared in 61% yield. The molecular structure of the adduct with maleic anhydride (1.6) is unequivocally established as 7-syn-trimethy1stannyl-endo- bicyclo[2.2.1]hept-5-enyl-2,3-dicarboxy1ic anhydride by single crystal X-ray structure analysis. In Part II, the high yield preparation of some new S-a1ky1-Saryl- N-p-toluenesu1fonylsu1foximines, by ruthenium tetroxide oxidation of the corresponding su1filimine, is described. Dehydrochlorination of S-chloroethy1-N-p-toluenesu1fonyl-S-p-toly1su1foximine and its S-phenyl analog with triethylamine gives the previously unknown N-p-to1uenesu1fony1- S-p-to1y1-S-viny1sulfoximine (II.17) and its S-phenyl analog. The Diels-Alder reaction of II.17 with a variety of 1,3-dienes and the known N-phtha1imido-S-p-tolyl-vinylsu1foximine (11.14) and the previously unreported S-p-nitropheny1-N-phtha1imido-viny1su1foximine (11.39) with cyclopentadiene are described. All of the reactions give mixtures of the possible adducts. The configuration of the major diastereomer (II.19d) of the adducts of II.14 with cyclopentadiene is known from a single crystal X-ray structure analysis. The structures of the other adducts are determined by ¹H NMR spectroscopic analysis. Chemical correlation of II.19d with the adducts of II.17 with cyclopentadiene confirm the assignment made by ¹H NMR. A competition Die1s-Alder reaction between II.17 and p-toly1-viny1sulfone shows that the vinylsulfoximine is more reactive. Sodium amalgam reduction of the cyclohexadienyl adducts of II.17 gives bicyclo[2.2.2Joctene and hydrazine in allyl alcohol reduction of adduct II.19d gives the corresponding sulfoxide II.20d.
150

General method for the synthesis of pseudodisaccharides : Diels-Alder approach to the synthesis of pseudodisaccharides

Abdullahi, Mohamed Hussain Haji January 2010 (has links)
This thesis describes a new method for the synthesis of pseudodisaccharides containing a carbasugar analogue attached to a "true" sugar. The methodology is based on a Diels-Alder cycloaddition of vinyl sugars and appropriately substituted pyran-2-ones, followed by chemical manipulation of the resulting cycloadducts. The thesis also describes the synthesis of inhibitors of Golgi α-mannosidase II and glucokinase. The first chapter is a comprehensive survey of the reported synthetic routes to pseudodisaccharides from the literature. The results and discussions are presented in chapter 2. This chapter starts by discussion of the preparation of vinyl sugars and pyran-2-ones and the regio- and stereoselectivity of their cycloadditions. This is followed by reporting the chemical manipulations of these cycloadducts and the synthesis of a pseudodisaccharide. Cycloadducts are shown to lose carbon dioxide at elevated temperatures to afford dihydrobenzenes. The loss of the bridging carbon dioxide from the cycloadducts is experimentally and computationally investigated. The resulting dihydrobenzenes are shown to also be useful as precursors in the synthesis of pseudodisaccharides. The chemical manipulation of these dihydrobenzenes is used towards the synthesis of a pseudodisaccharide. The third and fourth chapters focus on the synthesis of new inhibitors of Golgi α-mannosidase II and glucokinase respectively. A range of 6-aminoglucose and mannose derivatives were prepared and tested for the inhibition of Jack bean α-mannosidase, but were found to lack any inhibition. Similarly, a range of 6-triazologlucose derivatives were prepared but were found to lack any cytotoxicity. The fifth chapter contains the details of the preparation, experimental procedures and spectroscopic characterisation of the synthesised chemical compounds. Rate calculations are reported in Appendix I and the X-ray crystallographic data are presented in the Appendix II.

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