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.

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.

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.

Graduate

No description available.

Due to the ever increasing demand for the production of enantiopure drugs and biologically active compounds, the study of asymmetric synthesis and the production of more efficient and cost effective methods of obtaining chiral compounds suggests that there are expanding opportunities for Organic Chemists in this field. Of the broad range of chiral technologies available today for the synthesis of even the most complex multi-centre chiral molecules, the use of chiral auxiliaries continues to remain an important means of obtaining single enantiomer chiral compounds. In this investigation, the imidazolidinone chiral auxiliary (i) was synthesised in order to determine its efficiency and ability to transfer chiral information in Diels-Alder cycloaddition reactions. The products of such reactions are extensively used in the synthesis of natural compounds and pharmaceutical drugs. The synthesis of the imidazolidinone auxiliary is described and mention is made of the fact that the starting materials are cheap and readily available in both enantiomeric forms. The pathway involves only a single reaction that is easily carried out in moderate yields of 60-65%. An adaptation of this auxiliary is the cyclohexyl derivative (ii) which was obtained in a single hydrogenation step of (i) in very high yields (98%). This was compared to the synthesis of the bornane-1O,2-sultam auxiliary (ii). Although the starting materials are also cheap and readily available, there are more reaction steps involved. The synthesis of the imidazolidinone auxiliary proved to be much more simple as well as more time and cost effective. The huge advantage of these auxiliaries is the fact that they are both crystalline which facilitates their purification and that of their derivatives. A possible deficiency of the imidazolidinone auxiliary and the bornane-1O,2-sultam auxiliary was the fact that substitution reaction yields with various a,b-unsaturated acyl chlorides were consistently low (<50%). A major by-product of the acylation reaction was a 'double-adduct' compound that severely affected the reaction yields. This was overcome by employing a new method of acylation developed during the course of this research. It involves the use of DABCO as base with reaction yields between 60 and 98%. In addition to this, reaction conditions were mild and work up procedures simple. The N-acylimidazolidinone auxiliary proved to be extremely successful in Diels-Alder reactions with cyclopentadiene With results equalling those obtained with the well known and highly publicised bornane-10,2-sultam auxiliary. The scope of the N-acylimidazolidinone auxiliary in these reactions included the use of a- and b- substituted dienophiles. Although reactions with a-methyl and b-methyl substituted dienophiles were successful, the auxiliary proved to be unreactive with b-phenyl and b,b-dimethyl substituted dienophiles. The scope of dienes used was extended to include the relatively less reactive isoprene and 2,3-dimethyl-l,3-butadiene. Only the former reacted successfully in Diels-Alder reactions with the N-acylimidazolidinone auxiliary. Crystallinity was imparted to all the products except for the cyclohexyl derivative whose cycloaddition adducts only solidified on standing. The Diels-Alder adducts were successfully cleaved under standard reaction conditions to give products with ee's ranging from 95:5 to 99:1. This investigation also includes the use of the tertiary amine, DABCO, as a catalyst in the Diels-Alder reaction with, specifically, the N-acryloylimidazolidinone chiral auxiliary. Most examples of Diels-Alder reactions involve the use of Lewis acids as a means of improving the rate and selectivity of Diels-Alder reactions. DABCO not only increased the reactivity of the N-acryloylimidazolidinone auxiliary towards cyclopentadiene, but selectivity was also observed. An explanation was put forward as to the mechanism of the reaction as well as to the source of selectivity. Selectivity was much more pronounced in Diels-Alder reactions with the N-acryloylimidazolidinone auxiliary than with the N-acryloylbornane-10,2-sultam auxiliary. It was predicted that DABCO catalysed reactions are amenable to large scale procedures. Due to the fact that the diastereomeric cycloadducts are easily purified by recrystallization or chromatography, and together with the practical advantages and mild reaction conditions this could render the DABCO methodology with the N-acryloylimidazolidinone auxiliary industrially viable. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1997.

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Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Includes bibliographical references. / by Steven Edward Hall. / Ph.D.

Este trabalho mostra uma série de reações para a síntese de naftacendionas, partindo da l-acetilamino-4-hidroxi-9,10-antraquinona e seu produto de oxidação, a 4-acetilamino-9a-acetoxi-l,9, 10-antracenotriona, em presença de Pb(OAc)4. Estudou-se o comportamento da 4-acetilamino-9a-acetoxi- 1,9,10-antracenotriona frente a reagentes nuclefílicos de diferente natureza. Estas reações permitem o isolamento e a preparação de uma série de novos derivados antracênicos., úteis como intermediários sintéticos para outros amino-hidroxi-antracenos. / In this master work have been shown a series of reactions concern an the synthesis of naphthacendiones, starting from the l-acetylamine-4-hydroxy-9,10-anlhraquinone and its oxydation product the 4-acelylamine-ga-aceloxy-l~9,10-anthracentriane in presence of Pb(OAc)4. The behavior of the 4-acelylamine-9a-acelaxy-l,9,10- anthracentrione against nucleophylic reagents of different .nature have been studied. These reactions permit the isolation and preparation of a series of new anthracene derivatives useful as synlhelic inlermediales through other amine-hydraxyanthracenes and for analytical applications.