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There is no abstract available for this thesis. / Department of Chemistry

Note: / Recent years have witnessed a tremendous growth in the number of goldcatalyzeddevelop new gold catalytic methods to mediate carbon-carbon, carbon-oxygenand carbon-nitrogen bond forming reactions. Chapter 2 describes new annulations catalyzed by gold(I) of simple 0-hydroxyaldehydes with alkynes. This annulation efficiently generates isoflavanone-type structures, which have many possible applications in the synthesis of isoflavanone natural products. This chapter details the development and the optimization of the reaction conditions. The annulation was applied to various aldehydes and arylalkynes with good efficiency. Furthermore, it incorporated all atoms of both starting materials into the product and thus has a theoretical atom economy of 100%. Chapter 3 extends the scope of the annulations developed in Chapter 2. Indeed, 2,3-dihydro-l-tosylquinolin-3(1H)-one derivatives, aza-isoflavanones, have been efficiently synthesized via a gold-catalyzed annulation of 2-tosylaminobenzaldehyde and alkynes. The annulation was applied to various arylalkynes with good efficiency. This annulation can be used for the synthesis of a range of potentially bioactive molecules. [...] / Récemment nous avons constate une énorme croissance de l'utilisation de l'or comme nouveau catalyseur dans de nombreuses transformations chimiques sélectives. Le but de cette étude était de développer de nouvelles méthodes catalytiques en utilisant I' or pour former de nouveaux liens carbone-carbone, carbone-oxygène et carbone-azote. Dans le chapitre 2, nous décrirons la nouvelle addition catalysée par Por(I) entre des 2-hydroxyaldehydes et des alcynes. Cette addition produit des structures de type isoflavanones efficacement. Ces derniers sont impliques dans la synthèse de nombreux produits nature Is. L' addition a été appliquée efficacement diversaldéhydes et alcynes. En outre, l'addition a incorpore tous les atomes des produits de départ au produit final et a ainsi une économie d'atome théorique de 100%. Le développement et l'optimisation des conditions de réaction seront détailles dans ce chapitre.[...]

Recent years have witnessed a tremendous growth in the number of gold-catalyzed highly selective chemical transformations. The aim of this study was to develop new gold catalytic methods to mediate carbon-carbon, carbon-oxygen and carbon-nitrogen bond forming reactions. / Chapter 2 describes new annulations catalyzed by gold(I) of simple o-hydroxyaldehydes with alkynes. This annulation efficiently generates isoflavanone-type structures, which have many possible applications in the synthesis of isoflavanone natural products. This chapter details the development and the optimization of the reaction conditions. The annulation was applied to various aldehydes and arylalkynes with good efficiency. Furthermore, it incorporated all atoms of both starting materials into the product and thus has a theoretical atom economy of 100%. / Chapter 3 extends the scope of the annulations developed in Chapter 2. Indeed, 2,3-dihydro-1-tosylquinolin-3(1H)-one derivatives, aza-isoflavanones, have been efficiently synthesized via a gold-catalyzed annulation of 2-tosylaminobenzaldehyde and alkynes. The annulation was applied to various arylalkynes with good efficiency. This annulation can be used for the synthesis of a range of potentially bioactive molecules. / Chapter 4 describes applications in the total synthesis of the annulation developed in chapter 2. (+/-)-Pterocarpan and analogues have been efficiently synthesized via the annulation of salicylaldehydes and o-methoxymethoxylphenylacetylene followed by a one-pot reduction and acidic cyclization of the ketones. In addition, isoflavone derivatives have been synthesized rapidly via the annulation of salicylaldehyde and arylacetylenes followed by IBX/DMSO oxidation of the isoflavanones. / As part of our ongoing studies on metal-catalyzed atom economical reactions, the gold/silver-catalyzed addition of arenes to mono-substituted allene, generate exclusive terminal addition products are described in Chapter 5. / Finally, Appendix A explores the use of commercially available polymer-supported triphenylphosphine as a catalyst for the efficient gamma-addition of methyl 2-butynoate with various pronucleophiles. In addition, optimization studies shows no need of a co-catalyst for the reaction in the presence of a mixture of water:toluene (5:1). The polymer-supported triphenylphosphine is recoverable and can be reused efficiently. This gamma-addition is highly atom-economical and the reaction time was reduced under microwave irradiation.

Over the years, Giles and co-workers have established that, upon treatment with potassium tert-butoxide, tetra-substituted naphthalenes undergo cyclisations to afford naphthopyrans. It was suggested that these base-induced cyclisations was as a result of the reacting centers being forced into close proximity as a consequence of steric crowding.<br /> <br /> This thesis describes the synthesis of 3-allyl-4-ethyl-2-(1&prime / -hydroxyethyl)-1-methoxy-naphthalene 177 and its behaviour towards Pd(0) and potassium tert-butoxide under aerobic and anaerobic conditions, to verify whether the base-promoted cyclisations are indeed caused by the steric influences of the substituents. Two synthetic routes were attempted in the synthesis of the target naphthalene 177. The first of these attempted routes involved the conversion of 2-acetyl-4-hydroxy-1-methoxynaphthalene 182 into 2-acetyl-1-methoxy-4-trifluoromethanesulphonyloxy-naphthalene 191 and subsequently into 2-acetyl-4-ethyl-1-methoxynaphthalene 192 via Stille coupling. However, the subsequent Snieckus ortho-directed metalation reactions on the reduced 4-ethyl-2-(1&prime / -hydroxyethyl)-1-methoxynaphthalene 193, and analogues of it, to afford naphthalene 177 were unsuccessful. The second route entailed a Claisen rearrangement of the tri-substituted 2-acetyl-4-allyloxy-1-methoxynaphthalene 209 to afford the unstable tetra-substituted 2-acetyl-3-allyl-4-hydroxy-1-methoxynaphthalene 210, which was immediately converted into the corresponding 2-acetyl-3-allyl-1-methoxy-4-trifluoromethanesulpholnyloxynaphthalene 211. Stille coupling of the triflate 211 gave the 2-acetyl-3-allyl-4-ethyl-1-methoxy-naphthalene 212, which was subsequently reduced to the target naphthalene alcohol 177.<br /> The base-induced cyclisation studies performed on naphthalene 177, confirmed the hypothesis that these cyclisations of terta-substituted naphthalenes are indeed as a result of steric crowding.

The total synthesis of cyanindin-3-glucoside (C3G) appropriate for ��C enrichment at C-1` and C-6` has been achieved for metabolic studies. Construction of the phenolic ring-B was achieved by a Diels-Alder reaction employing a novel diene, (2R,3R)-2,3-dimethyoxy-2,3-dimethyl-5,6-dimethylene-1,4-dioxane, which incorporates a butane diacetal protecting motif. Reaction with a (labelled) dienophile affords the protected catechol. Formation of the flavone skeleton was achieved by condensation of the benzamide (ring-B) with an acetophenone (ring-A). Esterification of the flavone skeleton in ring-A was found to be essential for oxidation at C-3 with dimethyldioxirane affording the flavonol. Glycosylation using a glucosyl bromide gave the β-adduct exclusively which was reduced to the target compound, C3G. The overall synthetic design permits the synthesis of the labelled anthocyanin in nine steps (23%) from the dienophile.