Des oligocarbonates dihydroxytéléchéliques partiellement biosourcés ont été synthétisés par transcarbonatation en masse en faisant réagir l'isosorbide comme principal diol biosourcé et un diol aliphatique en tant que co-monomère avec du diphénylcarbonate en présence d'un catalyseur. Les oligomères ont été préparés en faisant varier le rapport des deux monomères diols. Les conditions de réaction ont été optimisées pour parvenir à une conversion totale en monomères tout en éliminant le phénol résiduel (sous-produit de la réaction). Les oligomères résultants portent des unités d'isosorbide à leurs deux extrémités de chaînes. La teneur en terminaisons hydroxyles a été déterminée par RMN-1H suivant une méthode de dérivatisation. Tous les oligocarbonates sont amorphes et leur Tg augmente avec l'augmentation de la teneur en isosorbide et avec la rigidité du co-monomère diol. Ces oligocarbonates ont été utilisés pour développer des revêtements polyuréthanne en ajoutant un polyisocyanate. Tous les revêtements obtenus sont transparents, brillants et présentent de très bonnes résistances aux solvants. Les propriétés thermiques, mécaniques et physico-chimiques des polyuréthanes dépendent à la fois de la structures de l’oligocarbonate et de celle du trimère d’isocyanate. / Partially bio-based dihydroxytelechelic oligocarbonates were synthesized by melt transcarbonatation polymerization using isosorbide as the principal bio-sourced diol and an aliphatic diol as co-monomer with diphenyl carbonate in the presence of a catalyst. The oligomers were prepared by varying the ratio of the two diol monomers. The reaction conditions were optimized to reach full conversion whilst also removing any residual phenol (by-product of the reaction). The resulting oligomers bear isosorbide units at both extremities. The hydroxyl group content is further determined by 1H-NMR according to a derivatization method. All the oligocarbonate diols were amorphous and their Tg increases with increasing isosorbide content and rigidity of the co-monomer diol. These oligocarbonates were used to develop polyurethane coatings by adding a polyisocyanate. All the coatings obtained are transparent, glossy and have a very good solvents resistance. The thermal, mechanical and physicochemical properties of polyurethanes depend on the structures of the oligocarbonate and the polyisocyanate used.

No description available.

Thesis advisor: Kian L. Tan / The acceleration of catalytic asymmetric silylation of syn-diols and triols by use of an azole additive has been developed. By simply adding 7.5-20 mol % of a commercially available small-molecule, 5-ethylthiotetrazole, to a previously reported chiral catalyst, reactions proceed within one hour delivering the desired products with similarly high yields and enantiomeric ratios; there is minimal reaction during the same period when one of the co-catalysts is absent. In an attempt to better understand this silylation mechanism, computational catalyst design and synthetic development were employed. / Thesis (MS) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Lysophosphatidic acid (LPA) and lysophosphatidylcholine (LPC) activity has been found to be dysregulated in cancer cells and therefore is a crucial target for research. Only a few LPA receptors have been identified to date, namely LPA 1, LPA 2, LPA 3, LPA 4 and peroxisome proliferator-activated receptors (PPAR). In order to identify receptors, we are designing and synthesizing bifunctional LPA and LPC activity probes to characterize their protein targets using activity based protein profiling (ABPP) among other proteomic technologies. By synthesizing bifunctional signaling probes that can mimic the naturally occurring LPA and LPC molecules and selectively capture receptors by virtue of their binding properties, we can identify and study the different proteins that are aberrantly expressed in various pathophysiological states such as cancer.

Calculation of bond angles from the available X-ray diffraction data for acenaphthene, indicated that the five-membered ring is planar and that cis-1,2-substituents are fully eclipsed and transsi.2-rsubstituents fully staggered in this ring system. These conclusions were confirmed by the ease of formation of cyclic carbonate and isopropylidene derivatives of the cis-acenaphthene-1,2-diol and the failure of the trans-isomer to form these new derivatives. The presence of intramolecular hydrogen bonds in the crystalline cis-diol and the absence of such bonds in the trans-diol also supported this structure. A single carbonyl stretching frequency of 1718 cm⁻¹ was found in the spectrum of pure acenaphthenequinone and the reported second band around 1770 cm⁻¹ was shown to be due to an impurity. A linear relation of the C=O and C-O-C stretching frequencies of the cis- and trans- diacetate and dibenzoate esters of the acenaphthene-1,2-diols was determined and compared with a similar relationship found for steroid esters. The dinitrate esters of the cis- and trans-acenaphthene-1,2-diols were prepared and characterized and the rates of their reactions with anhydrous pyridine were compared with!:those of other cyclic diol dinitrates. The dinitrates decomposed in a first order reaction with half lives of 90 and 610 minutes for the trans- and cis- isomers respectively at 25°C. A combination of chromatographic and spectrophotometry techniques was developed for rapid and accurate analyses of mixtures containing nitrate esters. An ultramicro-Kjeldahl procedure was developed for the determination of covalent nitrate nitrogen on a microgram scale. / Science, Faculty of / Chemistry, Department of / Graduate

The selective manipulation of hydroxyl groups in di- and polyols is a frequently encountered problem in organic synthesis. Such processes are often tedious and/or moderate yielding, and often necessitate multistep protection / deprotection sequences. Applying boron–diol interactions previously exploited in molecular recognition and based on methods previously developed in our research group, we have developed two classes of chemical transformations: 1. Regioselective sulfonylations of carbohydrate derivatives catalyzed by a borinic ester, providing access to the corresponding mono-tosylates in high yields; 2. Selective monoalkylations and monosulfonylations of structurally diverse 1,2- and 1,3-diol substrates.

The selective manipulation of hydroxyl groups in di- and polyols is a frequently encountered problem in organic synthesis. Such processes are often tedious and/or moderate yielding, and often necessitate multistep protection / deprotection sequences. Applying boron–diol interactions previously exploited in molecular recognition and based on methods previously developed in our research group, we have developed two classes of chemical transformations: 1. Regioselective sulfonylations of carbohydrate derivatives catalyzed by a borinic ester, providing access to the corresponding mono-tosylates in high yields; 2. Selective monoalkylations and monosulfonylations of structurally diverse 1,2- and 1,3-diol substrates.

No description available.

Le mycothiazole-4,19-diol, découvert en 2006, est une molécule naturelle isolée de l’éponge marine cacospongia mycofijiensis, dont il n’existe à ce jour aucune synthèse. La structure originale, combinée à la faible abondance naturelle et à une activité biologique potentielle du mycothiazole-4,19-diol font de cette molécule une cible synthétique attractive pour le chimiste organicien et constitue l’objectif de ces travaux de thèse. Le principal enjeu de cette synthèse est la construction du motif diol-1,2 allylique. Au total, quatre déconnections ont été étudiées. Pour chacune d’entre elles, plusieurs approches ont été effectuées afin de construire de manière efficace et élégante le mycothiazole-4,19-diol. Une étude sur l’utilisation du palladium en synthèse organique a également été effectuée au cours cette thèse. Parmi les nombreux systèmes catalytiques dans lesquels ce métal intervient, nous nous sommes intéressés à l’oxydation aérobique des alcools en leurs dérivés carbonylés. Nous avons élaboré un nouveau système permettant l’oxydation sélective des alcools allyliques. Les résultats obtenus sur la haute chimiosélectivité intramoléculaire font de cette méthode un outil puissant et efficace et a été mis à profit dans le cadre des approches du mycothiazole-4,19-diol. Une étude supplémentaire réalisée sur l’utilisation du palladium en réactions séquentielles a également été menée avec l’élaboration d’un processus oxydation aérobique-formation de liaison C-C par couplage de Heck. L’originalité de la méthodologie développée est que le catalyseur intervient dans deux réactions totalement différentes permettant ainsi la synthèse rapide de molécules relativement complexes à partir de substrats simples. / Mycothiazole-4,19-diol is a natural compound isolated in 2006 from a marine sponge cacospongia mycofijiensis which has never been synthesized. Its unique structure, its weak abundance and its potential biological activity make mycothiazole-4,19-diol an attractive target in organic chemistry. The challenge is the building of allylic diol-1,2 moiety. In order to make a concise and elegant synthesis of this molecule, four disconnections and many approaches have been studied. A study about the use of palladium in organic synthesis has also been done. Among all the catalytic systems in which this metal is involved, we were first interested in the aerobic oxidation of alcohols into their corresponding carbonyl compounds. We have elaborated a new catalytic system which enables the selective oxidation of allylic alcohols. This methodology has been applied in the different synthetic approaches towards the mycothiazole-4,19-diol. A second study has been done about the use of palladium in sequential processes. We have elaborated a new catalyzed process with two sequential different steps: allylic alcohol oxidation-Heck reaction. The originality of this system is that the catalyst is involved in both reactions which makes an easy access to functionalized α,β-unsaturated ketones from allylic alcohols.

The research presented in this thesis focuses on the study of the reaction between boronic acids and diols and its evaluation as a possible "click" reaction, possibly applicable in bioconjugation and drug delivery. A key feature of this reaction is its reversibility at acidic pH, which could allow the release of a diol-containing drug from a bioconjugate in the acidic environment of late endosome/lysosome, possibly after undergoing receptor mediated endocytosis. Over the last two decades various studies have focused on the study of the conjugation of boronic acids to diols using Alizarin Red S as a fluorescence reporter. In this research we have presented an alternative method based on the batochromic shifts of Alizarin Red S absorbance; this method is particularly advantageous in complex systems with an elevated scattering, such as colloidal dispersions or for binding to complexed active compounds. We have therefore demonstrated that this method allows the determination of equilibrium constants between diols (e.g. catecholamines) and boronic acids. We have also demonstrated that the method allows to follow the kinetics of enzymatic reactions involving catechols; in particular, we have focused on cytochrome P450-mediated reactions such as the conversion of estradiol to 2-hydroxyestradiol using CYP1A2, or the demethylation of 3-methoxytyramine to dopamine using CYP2D6. Once we have established a reliable method for following this reaction on low molecular weight compounds, we have applied it to polymeric bioconjugates. Specifically, we have selected hyaluronic acid (HA) as a biocompatible and biodegradable polymeric backbone and produced derivatives containing boronic acids, catechols and dimethylated catechols (as negative controls). The resulting polymers where characterised via UV-Vis, 1H NMR and SLS, also qualitatively evaluating their cytotoxicity and enzymatic degradability. The conjugates with boronic acids showed the lowest cytotoxicity, and the highest degradability. The complexation of HA-boronic derivatives was then studied; using the same library of diols previously used with low molecular weight compounds, evaluating the effect of the presence of the polysaccharidic macromolecular chain.