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The work herein comprises two distinct projects: the first involves the construction of allylic ketones and enones directly from primary alcohols, using a novel one-pot procedure. Following development of this methodology, its application to the synthesis of indolizidine alkaloid elaeokanidine A was investigated. The second research area concerns the development of a copper(II)-catalysed radical cyclisation reaction to form spirocyclic oxindoles directly from linear anilides, along with subsequent preliminary studies towards to the synthesis of spirotryprostatin A.

This thesis focuses on the use of unsaturated aldols as useful substrates in natural product synthesis. Two methodologies have been investigated for the asymmetric synthesis of highly substituted lactones containing multiple contiguous stereocentres from unsaturated aldol precursors. These lactones have potential application as building blocks for natural product synthesis. Firstly, synthetic applications of the retro aldol reaction are reviewed. The second chapter describes a novel methodology for the asymmetric synthesis of highly substituted δ-lactones from syn-aldol cyclopropanes iii. Mercury mediated cyclopropane ringopening of the methyl ester cyclopropanes iv followed by concomitant cyclisation produced organomercurial δ-lactones v, which subsequently undergo reductive demercuration in basic sodium borohydride to afford the highly substituted δ-lactones vi in good yield and excellent diastereoselectivity. The scope of this method was investigated with variation of the R1 and R2 groups. The synthetic utility of this process was also demonstrated with the synthesis of a series of (+)-Prelactone natural products. The third chapter decribes a method of preparing hydroxy-γ-butyrolactones (viii-x) containing multiple contiguous stereocentres in high yield with good diastereoselectivity. Upjohn dihydroxylation conditions using catalytic osmium tetroxide were employed to β-alkenyl-β- hydroxy-N-acyloxazolidin-2-ones vii with different alkene substitution patterns. This resulted in the formation of triols that underwent spontaneous intramolecular 5-exo-trig cyclisation reactions to afford hydroxy-γ-butyrolactones viii, ix or x depending on the substitution pattern of the alkene precursor.

Chapter One gives an introduction to the key concepts of bridgehead alkene formation and its relevance to the formation of bridgehead enolates of ketones including a review of bridgehead enolates in synthesis. The review is limited to the generation of bridgehead carbanions alpha to a carbonyl group and does not cover bridgehead cations, radicals or any anions except those already mentioned. In addition, a brief introduction to chiral base methodology and a review of the latest developments is included. Chapter Two describes the generation of bridgehead enolates in various bridged bicyclic ketones using chiral and achiral lithium amide bases and their subsequent interception with chlorotrimethylsilane. The chiral bridgehead silanes resulting from enantioselective deprotonation were shown to undergo silyl exchange reactions with TBAT as fluoride source in the presence of various electrophiles. Chapter Three describes a review of bridgehead enolates of imides and describes the extension of the developed methodology in Chapter Two to the generation and trapping of bridgehead enolates in bridged bicyclic imides and lactams. In addition bridgehead enolates are shown to react in the presence of non-classical in situ electrophiles such as methyl iodide, allyl bromide, benzyl bromide, prenyl bromide and pivaloyl chloride in high yield and enantioselectivity. The secondary bridgehead deprotonation of monosubstituted imides was also achieved resulting in double bridgehead functionalised products with high ee. The bridgehead silanes are shown to undergo silyl exchange reactions and display silyl directed regioselective reduction and thionation reactions. The mechanism of deprotonation, comparison to known examples and the origin of bridgehead carbanion stability are discussed. Chapter Four contains the experimental procedures and analytical data for the preparation of the novel compounds described herein followed by the appendix of selected NMR and X-ray data.

L’oxydation catalytique du propylène en acroléine en phase gazeuse est un procédé complexe et fortement exothermique, faisant intervenir de nombreuses réactions consécutives et compétitives. Une des clés pour maximiser le rendement en acroléine est le contrôle rigoureux de la température du mélange réactionnel ; il s’agit de lever les limitations aux transferts thermiques, afin d’évacuer l’importante chaleur de réaction. Un échangeur-réacteur milli-structuré a ainsi été retenu pour intensifier le procédé. En effet, de par la taille millimétrique de ses canaux ainsi que le choix d’un dépôt du catalyseur industriel sur les parois internes de ceux-ci, les transferts de chaleur et de matière sont améliorés. Afin de réaliser ce dimensionnement, une étude préliminaire de la cinétique des réactions a été réalisée et un modèle cinétique a été déterminé. Ce dernier a été utilisé afin de dégager les conditions optimales de fonctionnement d’un canal réactif (température, nombre de canaux composition), et afin d’extrapoler ces conditions sur un agencement structuré des canaux réactifs. La forme des chambres de distribution et de collecte du réacteur-échangeur ainsi que sa structure ont été déterminées et optimisées afin d’atteindre un rendement élevé par un contrôle optimal de la température, de minimiser la maldistribution des fluides et d’assurer la sécurité du procédé. Ce réacteur-échangeur intensifié, à la géométrie complexe, a finalement été fabriqué par impression 3D, au sein du projet français FAIR (Fabrication Additive pour l’Intensification des Réacteurs) / The catalytic oxidation of propylene to acrolein is a complex and highly exothermic process carried out in the gas phase, involving consecutive and competitive reactions. To maximize the efficiency of this process, the temperature needs to be rigorously controlled and the thermal transfers must be maximized, in order to evacuate the heat released by the reactions. A millistructured reactor-exchanger has thus been chosen to intensify this process. Indeed, millimetric channels washcoated with an industrial catalyst provide intensified heat and mass transfer. To carry out this design, a preliminary study of the kinetics of these reactions was carried out and a kinetic model was determined. This model was then used to identify the optimal operating conditions of a single reactive channel (temperature, number of channels, composition), and to extrapolate these conditions for the design of an intensified reactor exchanger. The shape of the distribution and collect chambers of these reactive channels were then optimized to minimize maldistribution, maximize the acrolein yield with an optimal control of the temperature, and to ensure the safety of the process. This intensified reactor-exchanger with complex geometry was finally manufactured by 3D printing, within the French project FAIR (Additive Manufacturing for the Intensification of Reactors)

La déshydratation du glycérol en acroléine en phase gazeuse sur catalyseur solide a été étudiée pour comprendre la formation des sous-produits, déterminer un mécanisme réactionnel et expliquer la désactivation du catalyseur. Les expériences ont été réalisées dans un réacteur isotherme à lit fixe sous différentes conditions opératoires. Pour déterminer les chemins réactionnels de la réaction, de nombreux sous-produits ont été passés séparément sur le catalyseur. Une chromatographie gazeuse en ligne, en continu et originale a été utilisée pour analyser tous les produits de la réaction simultanément. Deux produits ont été quantifiés par chromatographie liquide et de nouveaux composés ont été identifiés par chromatographie gazeuse couplée à un spectromètre de masse. Un mécanisme réactionnel a été proposé. Pour comprendre la désactivation du catalyseur, les produits responsables du dépôt carboné ont été identifiés et la chute de la conversion du glycérol au cours du temps a été modélisée / Glycerol dehydration to form acrolein in gas phase over a solid acid catalyst was studied to understand by-products formation, to determine a detailed mechanism and to explain the deactivation process. Experiments were run in an isothermal fixed bed reactor under different operating conditions. To understand the multiple pathways of the glycerol dehydration mechanism, many by-products of the reaction were passed separately over the catalyst. An original multivalve on-line gas chromatography was used to analyze the whole reaction products continuously and simultaneously. Two products were quantified by high performance liquid chromatography, and the unknown products were identified by gas chromatography-mass spectrometry. A detailed reaction mechanism was then proposed. In order to understand the deactivation process, compounds responsible of carbon deposit were identified and the glycerol conversion fall during an experiment was modelled