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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

Etude des propriétés de commutation de composés en série indolino-oxazolidine par spectroscopie RMN et calculs DFT / Study of the switching behavior of indolino-oxazolidine derivatives by NMR spectroscopy and DFT calculations

Guerrin, Clément 28 September 2018 (has links)
Les composés moléculaires étudiés présentent une fonction indolino-oxazolidine (Box) et une jonction éthylénique (lié à un groupement thiényle – Box simples) qui sont toutes deux commutables chimiquement ou photochimiquement entre deux états. Le suivi des réactions associées a été réalisé en solution par spectroscopie RMN 1H afin de caractériser les différents états de commutation de ces composés. L’ouverture de la fonction Box peut être provoquée par ajout d’acide ou par irradiation dans l’UV (chloroforme), et ce processus est réversible en présence de base. Quel que soit l’état de la Box, l’isomérisation trans  cis de la jonction éthylénique est photochimique par irradiation à 436 nm alors que la réaction inverse est spontanée et thermique. Des composés comportant deux fonctions Box et deux jonctions éthyléniques liées à un groupement aromatique phényle ou bithiényle (BiBox) ont également été étudiés et des processus de commutation similaires ont été observés entre un nombre d’états supérieur du fait de la présence de quatre entités commutables. La commutation entre les différents états a donc été montrée et est déterminé le stimulus le plus adapté pour donner un été sélectivement et quasi quantitativement. Des calculs de chimie quantique de DFT et de TD-DFT ont permis de caractériser les structures moléculaire et électronique de chacun des états de commutation des Box simples ainsi que certains états des systèmes BiBox et de rationaliser certaines observations expérimentales. Des propriétés de fluorescence ont été observées et les spectres d’émission mesurés et les rendements quantiques de fluorescence calculés en fonction de l’état ouvert ou fermé de la (des) Box. / Molecular systems studied here present an indolino-oxazolidine (Box) moiety and an ethylenic junction (linked to a thienyl residue – Box simple) which are both chemically and photochemically switchable between two states. The switching reactions were followed in solution by 1H NMR spectroscopy in order to characterize the different metastable states. Opening of the Box moiety can be triggered upon acidification or by UV irradiation in chloroform and the reaction is reversible upon neutralization with base. Whatever the closed/open state of the Box moiety is, ethylenic junction trans  cis isomerization is photochemically driven by 436 nm irradiation, whereas the reverse reaction is thermally spontaneous. Compounds with two Box moieties and two ethylenic junction linked together by a phenyl or bithienyl aromatic bridge (BiBox) have also been studied and similar switching behavior have been observed between much more states due to the presence of four switchable functions. Thus, the commutation between different states has been shown and most suitable stimulus to convert selectively and almost quantitatively from one state to another have been evidenced. Based on DFT and TDDFT methods, quantum chemistry calculations allowed to characterize molecular and electronic structures of the four switching states for Box simple systems and of some of BiBox and to rationalize some experimental observations. Fluorescence properties being surprisingly observed and so, then emission spectra and corresponding fluorescence quantum yields have been determined. The fluorescence data depend on the open/closed state of the Box moieties, allowing additional properties to these compounds.
2

The decomposition of 5-substituted 3-nitroso-2-oxazolidones /

Weinberg, Alan Edward January 1956 (has links)
No description available.
3

Correlation of the acid-catalyzed hydrolysis rates of some oxazolidines with substituent effects /

Cleary, Robert W. January 1964 (has links)
No description available.
4

A study of the configuration and hydrolysis of some oxazolidines derived from the ephedrines /

DeNeale, Richard Jay January 1973 (has links)
No description available.
5

Synthèse d'oxazolidines et de pyrrolidines trifluorométhylées chirales : applications en synthèse asymétrique / Synthesis of chiral trifluoromethylated oxazolidines and pyrrolidines : applications in asymmetric synthesis.

Lubin, Hodney 19 November 2010 (has links)
L'oxazolidine trifluorométhylée (trans-Fox) dérivée du (R)-phénylglycinol a été préparée sous forme diastéréoisomériquement pure par résolution dynamique induite par la cristallisation d'un mélange d'oxazolidines cis et trans.La trans-Fox a été utilisée avec succès comme auxiliaire chiral pour des réactions d'hydroxylation par l'oxygène moléculaire et de fluoration électrophile d'énolates d'amide ainsi qu'en réarrangement sigmatropique [2,3] d'amines allyliques. Après clivage, des composés énantiomériquement purs d'une grande importance synthétique sont obtenus.Une voie d'accès à des pyrrolydines trifluorométhylées chirales a été mise au point à partir de la trans-Fox. La trans 2-phenyl-5-trifluoromethylpyrrolidine a été utilisée comme auxiliaire chiral pour des réactions d'alkylation asymétriques. / The trifluoromethylated oxazolidine (trans-Fox) derived from (R)-phenylglycinol was prepared as a single diastereoisomer by a cristallisation induced dynamic resolution of a mixture of cis and trans oxazolidines.The trans-Fox was used with success as a chiral auxiliary for hydroxylation by oxygen and electrophilic fluorination of amide enolates reactions and [2,3] sigmatropic rearrangements of allylic amines. After deprotection, very synthetically useful enantiomerically pure compounds were obtained.An acces to chiral trifluoromethylated pyrrolidines was developped starting from trans-Fox. The trans 2-phenyl-5-trifluoromethylpyrrolidine was used as a chiral auxiliary for asymmetric alkylation reactions.
6

Nouveaux composés photochimiques dédiés aux applications optiques non linéaires

Mançois, Fabien 18 December 2009 (has links)
Lors de ce travail de thèse, nous avons effectué des recherches sur des chromophores organiques. Notre étude s’est portée sur la commutation des propriétés optiques linéaires et non linéaires via l’étude d’interrupteurs organiques multi-adressables. Notre étude s’est portée plus particulièrement sur la famille des dérivés de l’indolino-oxazolidine. Ce type de molécule présente l’avantage d’avoir deux voix de commutations distinctes par photochromisme et acidochromisme. Nous avons recherché le lien entre la structure des molécules et leurs propriétés optiques par une étude combinée originale théorie/expérience avec l’utilisation de calculs quantiques sophistiqués et par diffusion hyper-Rayleigh de la lumière. / In this work we have investigated the commutation of linear and non linear optical properties in organic multifunctional switches. Indolino-oxazolidine compounds and their derivatives were chosen as example of multifunctional systems, because they combine both acidochromic and photochromic properties. The relationships between the molecular structure of these compounds and their optical properties were established by means of high level the quantum chemical approach and hyper-Rayleigh Scattering of light approaches.
7

1,3-Oxazoline-2-thiones saccharidiques : synthèse et réactivité de structures bio-actives originales / Carbohydrate-based 1,3-oxazoline-2-thiones as original bioactive structures

Silva, Sandrina Ribeiro Martins da 11 September 2009 (has links)
A nos jours, la résistance des microorganismes aux antibiotiques est l'un des plus gros problèmes de la santé publique. La recherche de nouvelles familles de composés naturelles ou synthétiques nous amène vers la découverte des méthodologies innovantes conduisant à de nouveaux antibiotiques. Dans le présent travail, nous vous invitons à plonger dans le "nouveau monde" de la synthèse, la réactivité et l'activité biologique de 1,3-oxazoline-2-thiones (OXTs). En effet, cet hétérocycle peu exploré est un facilement obtenu par condensation entre _-hydroxycarbonyle et l'acide thiocyanique. Lorsque l'hétérocycle est ancré sur un modèle de glucides, des structures originales sont attendus tels que OZTs fusionnées à cinq ou six chaînons et OXTs liées par une liaison C-C aux sucres, avec un vaste potentiel chimique et biologique. Nous avons alors étudié la synthèse et la réactivité de OXT simple et thionocarbamates fusionnées ou liés à des glucides modèles, conduisant à la formation de nouveaux carbohydrates fusionnées aux oxazolidinones (OZOs) ainsi que des pseudo C-iminosucres et oxazoles. Nous avons également exploré l'électrophilie de la fonction thioamide dans les couplages croisés de type Suzuki et Stille. Une nouvelle modification de la réaction de Sonogashira a été élaborée en utilisant le cuivre (I) comme cofacteur en quantité catalytique, et sa faisabilité a été démontrée pour une variété de substrats. / The resistance of microorganisms to antibiotics is, in our days, one of the biggest problems in terms of public health. The research for new artificial and natural families of compounds throws us towards innovative methodologies leading to novel antibiotics.In the present work, we are invited to dive in the “new world” of 1,3-oxazoline-2-thiones (OXTs) synthesis, reactivity and biological activity. In fact, this unexplored heterocycle is a simple synthon readily obtained by condensation of thiocyanic acid with an _-hydroxycarbonyl species. When the heterocycle is anchored on a carbohydrate template, original structures are expected such as OZTs fused to five- or six-membered rings and OXTs C-C linked to sugars, with a broad potential in organic chemistry and bioorganic applications. We have then investigated the synthesis and reactivity of simple OXT and thionocarbamates fused or linked to carbohydrate templates, leading to the formation of new carbohydrate-fused oxazolidinones (OZOs) as well as pseudo-C-iminosugars and oxazoles. We have also explored the use of thioxo compounds as electrophiles in Pd-assisted cross-coupling methods, such as Suzuki and Stille reactions. A new modified Sonogashira cross-coupling reaction, in which copper (I) is used in catalytic amount, was developed and its feasibility was proven for a variety of substrates. Finally, our attention was focused on the biological potential of the new molecules. We have targeted a broad spectrum of antimicrobial activity for some OXTs and OZTs, to which was added a screening of glycosidases inhibition for the pseudo C-iminosugars.
8

Nouvelles applications de la réaction de Passerini dans des réactions de type Friedel-Crafts et Tsuji-Trost. / New applications of Passerini reaction in Friedel-Crafts and Tsuji-Trost reactions.

Elmamouni, Elhachemia 02 March 2017 (has links)
L’élaboration de synthèses rapides et efficaces de molécules complexes à partir de substrats de départ simples en utilisant un minimum d’étapes constitue un véritable enjeu de la chimie organique contemporaine. Dans ce contexte, les réactions multicomposant, grâce à leur capacité à créer plusieurs liaisons en une étape, offrent une grande efficacité pour synthétiser des structures d’une grande complexité moléculaire. Par ailleurs, la catalyse organométallique s’est considérablement développée ces dernières années, pour devenir un outil de choix pour la formation de liaisons carbone-carbone. La réaction de Tsuji-Trost est notamment un des plus connues dans ce domaineDans le cadre de cette thèse, la découverte de post-condensations originales à partir d’adduits obtenus par les réactions multicomposant impliquant un isonitrile est l’axe majeur de nos recherches. Ces réactions permettent un accès efficace à un large éventail de composés hétérocycliques.Tout d’abord, nous avons développé une nouvelle voie efficace de synthèse des indolylacétamides via une cascade Passerini/Friedel-Crafts à partir d’adduits de Passerini et d’indoles en présence d’un acide de Lewis. Une version monotope de cette cascade a été ainsi développée.Par ailleurs, nous avons exploité la réactivité des hydrazones N-monosubstitués en tant que bis-nucléophile 1,3 en vue de préparer divers dérivés de 2-pyrazolines via une cascade Tsuji-Trost/Cyclisation pallado-catalysée à partir des adduits de Passerini ou de phosphonates. Dans le but de préparer des 2-pyrazolines énantiosélectivement enrichis, une version énantiosélective de cette cascade a été également réalisée à partir d’adduits de Passerini.Enfin, la mise au point d’une nouvelle cascade Tsuji-Trost/Cyclisation exploitant l’allyle méthyle carbonate a permis l’accès rapide à des motifs hétérocycliques de type oxazolidine-2,4-diones en exploitant le dioxyde de carbone généré in situ. / The development of rapid and efficient syntheses of complex molecules from simple starting substrates using a minimum of steps is a real challenge of contemporary organic chemistry. In this context, multicomponent reactions, thanks to their ability to create several one-step bonds, offer a high efficiency in synthesizing structures of great molecular complexity. Moreover, organometallic catalysis has developed considerably in recent years, becoming a tool of choice for the formation of carbon-carbon bonds. The Tsuji-Trost reaction is specially well known in this field.In this thesis, the discovery of the original post-condensations from the adducts obtained by multicomponent reactions involving isonitrile is the major axis of our research. These reactions allow efficient access to a wide range of heterocyclic compounds.First, we have developed a new efficient pathway for the synthesis of indolylacetamides via the Passerini/Friedel-Crafts cascade from the Passerini adducts and indole in the presence of a Lewis acid. A one-pot version of this cascade has been also developed.Furthermore, we have exploited the reactivity of N-monosubstituted hydrazones as 1,3-bis-nucleophile in order to prepare various 2-pyrazoline derivatives via a pallado-catalyzed Tsuji-Trost/Cyclisation cascade from the Passerini adducts or Phosphonates. In order to prepare enantioselectively enriched 2-pyrazolines, the enantioselective version of this cascade was also realized from the Passerini adduct.Finally, the development of a new Tsuji-Trost/Cyclization cascade from the Passerini adducts and the allyl methyl carbonate provide straight fast and efficient access to oxazolidine-2,4-diones heterocyclic units by exploiting the carbon dioxide generated in situ.
9

Estudo da adição aldólica do éster terc-butílico da n-(difenilmetileno)glicina a alguns aldeídos aromáticos / Study aldol addition of the tert-butyl ester of n- (diphenylmethylene)glycine to some aromatic aldehydes

Campiotti, Valmir 07 March 2016 (has links)
As reações de adição aldólica entre a cetimina 1 e aldeídos aromáticos foram inicialmente efetuadas à temperatura ambiente, em sistema bifásico constituído por uma fase aquosa básica (KOH 10% ou NaOH 5% m/v) e por uma fase orgânica (aldeído), na ausência de solventes e de catalisadores, observando-se baixa conversão em produto. Porém, quando se utilizou o catalisador aliquat®-336, foi possível reduzir a concentração da base (NaOH 1%), com conversão total da imina em produto que, na maioria dos casos, era uma mistura de duas oxazolidinas isoméricas de estereoquímica cis e trans. Esses compostos puderam ser isolados e purificados por recristalização de etanol ou metanol. Em todas as reações efetuadas com benzaldeído, m-clorobenzaldeído e p-nitrobenzaldeído, não se observou excesso diastereomérico significativo. No entanto, as reações com p-clorobenzaldeído mostraram-se diastereosseletivas, conduzindo, à temperatura ambiente, quase que exclusivamente à oxazolidina de estereoquímica cis. A comparação entre o resultado de reações efetuadas a curto e longo tempo de reação, ou em diferentes temperaturas, permitiu concluir que o aldol de estereoquímica anti é o produto cinético, o qual se transforma lentamente na oxazolidina cis. O produto termodinâmico (aldol syn) cicliza rapidamente, não sendo observado nos espectros de RMN de H dos produtos brutos de reação, mas sim seu produto ciclizado, a oxazolidina trans. Tentativas de obter os produtos de reação com excesso enantiomérico, pelo emprego de catalisadores de transferência de fase assimétricos, não foram bem sucedidas. / The aldol addition reactions of ketimine 1 with four aromatic aldehydes could be performed at room temperature, in the presence of an alkaline aqueous solution (KOH 10% or NaOH 5% m/v), and in the absence of organic solvents or catalysts. Under this conditions, conversion to product was often incomplete. However, when the reaction was performed in the presence of aliquat®-336, the base concentration could be reduced (1% m/v), and the ketimine was completely converted into a mixture of diastereomeric oxazolidines, that could be isolated and purified by crystallization from ethanol or methanol. Although no significative diastereomeric excess was observed for the reactions of 1 with benzaldehyde, m-chlorobenzaldehyde or p-nitrobenzaldehyde, for reactions with p-chlorobenzaldehyde the cis oxazolidine was almost exclusively formed. The comparison of diastereomeric ratio at shorter or longer reaction times seems to indicate that the aldol anti adduct is the kinetic product and that cyclization to the corresponding cis oxazolidine is slower than the retro-aldol reaction. On the other hand, in lieu of the thermodynamic product (aldol syn), only the corresponding cyclized product (oxazolidine trans) could be visualized in the H NMR spectra of the crude product, as a result of a fast cyclization step. Attempts to produce enantiomeric enriched oxazolidines by performing the aldol reactions in the presence of chiral catalysts were unsuccessful.
10

Estudo da adição aldólica do éster terc-butílico da n-(difenilmetileno)glicina a alguns aldeídos aromáticos / Study aldol addition of the tert-butyl ester of n- (diphenylmethylene)glycine to some aromatic aldehydes

Valmir Campiotti 07 March 2016 (has links)
As reações de adição aldólica entre a cetimina 1 e aldeídos aromáticos foram inicialmente efetuadas à temperatura ambiente, em sistema bifásico constituído por uma fase aquosa básica (KOH 10% ou NaOH 5% m/v) e por uma fase orgânica (aldeído), na ausência de solventes e de catalisadores, observando-se baixa conversão em produto. Porém, quando se utilizou o catalisador aliquat®-336, foi possível reduzir a concentração da base (NaOH 1%), com conversão total da imina em produto que, na maioria dos casos, era uma mistura de duas oxazolidinas isoméricas de estereoquímica cis e trans. Esses compostos puderam ser isolados e purificados por recristalização de etanol ou metanol. Em todas as reações efetuadas com benzaldeído, m-clorobenzaldeído e p-nitrobenzaldeído, não se observou excesso diastereomérico significativo. No entanto, as reações com p-clorobenzaldeído mostraram-se diastereosseletivas, conduzindo, à temperatura ambiente, quase que exclusivamente à oxazolidina de estereoquímica cis. A comparação entre o resultado de reações efetuadas a curto e longo tempo de reação, ou em diferentes temperaturas, permitiu concluir que o aldol de estereoquímica anti é o produto cinético, o qual se transforma lentamente na oxazolidina cis. O produto termodinâmico (aldol syn) cicliza rapidamente, não sendo observado nos espectros de RMN de H dos produtos brutos de reação, mas sim seu produto ciclizado, a oxazolidina trans. Tentativas de obter os produtos de reação com excesso enantiomérico, pelo emprego de catalisadores de transferência de fase assimétricos, não foram bem sucedidas. / The aldol addition reactions of ketimine 1 with four aromatic aldehydes could be performed at room temperature, in the presence of an alkaline aqueous solution (KOH 10% or NaOH 5% m/v), and in the absence of organic solvents or catalysts. Under this conditions, conversion to product was often incomplete. However, when the reaction was performed in the presence of aliquat®-336, the base concentration could be reduced (1% m/v), and the ketimine was completely converted into a mixture of diastereomeric oxazolidines, that could be isolated and purified by crystallization from ethanol or methanol. Although no significative diastereomeric excess was observed for the reactions of 1 with benzaldehyde, m-chlorobenzaldehyde or p-nitrobenzaldehyde, for reactions with p-chlorobenzaldehyde the cis oxazolidine was almost exclusively formed. The comparison of diastereomeric ratio at shorter or longer reaction times seems to indicate that the aldol anti adduct is the kinetic product and that cyclization to the corresponding cis oxazolidine is slower than the retro-aldol reaction. On the other hand, in lieu of the thermodynamic product (aldol syn), only the corresponding cyclized product (oxazolidine trans) could be visualized in the H NMR spectra of the crude product, as a result of a fast cyclization step. Attempts to produce enantiomeric enriched oxazolidines by performing the aldol reactions in the presence of chiral catalysts were unsuccessful.

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