La fonctionnalisation de liaisons C-H réputées peu réactives ouvre de nouvelles perspectives en synthèse organique. La catalyse par un métal de transition comme le palladium représente une solution particulièrement efficace à ce problème. Les travaux de thèse présentés dans ce mémoire s’inscrivent dans ce contexte. Dans un premier temps, la réaction étudiée, catalysée par le palladium, a visé à étendre une méthodologie mise au point au laboratoire pour la synthèse de carbocycles et d’hétérocycles à cinq chaînons par activation intramoléculaire de liaisons C(sp3)-H à partir de chlorures d’aryles. Ces derniers sont en effet plus disponibles et moins onéreux que les bromures d’aryle correspondants. Des études d’optimisation ont été effectuées pour la mise au point d'une réaction diastéréosélective et régiosélective. Plusieurs substrats ont été synthétisés pour être ensuite placés dans les conditions optimales de la réaction d’activation C(sp3)-H, et ont conduit à une grande diversité de cycles à cinq chaînons fusionnés. Dans un deuxième temps, nos travaux ont consisté à étendre l’activation C(sp3)-H pallado-catalysée à des précurseurs non aromatiques cycliques ou acycliques. Pour des raisons d'accessibilité, nos études se sont alors portées sur la préparation de bromures vinyliques azotés pouvant conduire après activation C-H à des motifs hexahydroindoles ou pyrrolidines. De nouvelles conditions d’activation CH ont alors été trouvées pour cette famille de substrats, et ont conduit aux hétérocycles cibles de manière diastéréosélective et régiosélective. Après extension de la réaction à divers précurseurs, nous nous sommes intéressés à la synthèse d’un intermédiaire poly-fonctionnalisé permettant d'accéder aux aéruginosines, famille de produits naturels bioactifs. / The direct functionalization of unactivated C-H bonds represents an atom- and step-economical alternative to more traditional synthetic methods based on functional group transformation, which often require multi-step sequences. In particular, transition-metal catalysis has recently emerged as a owerful tool to functionalize otherwise unreactive C-H bonds. In this context, we first investigated the extension of a methodology that has been developed in our laboratory for the synthesis of fused five-membered rings via palladium-catalyzed C(sp3)-H activation from aryl chlorides. Optimization studies were conducted and reaction conditions leading to a regioand diastereoselective process were found. These optimal conditions were applied to various ubstrates, giving rise to a variety of fused five-membered carbocycles and heterocycles. Next, our work was devoted to the extension of the palladium-catalyzed C(sp3)-H activation to cyclic and acyclic non aromatic precursors. Our studies focused on the preparation of the more accessible nitrogen-containing bromoalkene substrates, leading to interesting hexahydroindole or pyrrolidine motifs by C-H activation. New C-H activation conditions were adapted to this family of substrates and led to the synthesis of the target heterocycles in a regio- and diastereoselective manner. As a more complex application of this method, we investigated the synthesis of a polyfunctionalized intermediate allowing the access to the aeruginosin family of bioactive natural products.

The field of metal-catalyzed C–H bond functionalizations is an incredibly vibrant and spans beyond the formations of biaryl motifs. The introduction chapter will cover the mechanistic aspects of the C–H bond functionalization with metal-carboxylate complexes. The mechanistic facets of this reaction will be the main conducting line between the different sections and chapters of the first part of this thesis. In the second chapter, will be described additives that can readily promoted C–H bond arylation of poorly reactive substrates. More specifically, we will revisit the intramolecular direct arylation reaction we will demonstrate the effect of pivalic acid as a co-catalyst by developing milder reaction conditions. In the third chapter we be described experimental and computational studies which suggested that the a single pathway might be involved in the palladium-catalyzed C–H bond functionalization of a wide range of (hetero)arene. Following this we will describe a general set of conditions for the direct arylation of wide range of heteroarenes. Also, we will present two different strategies to selectively and predictably arylate substrates containing multiple functionalizable C–H bonds. In the fourth chapter will be presented our efforts toward the development of new C–H bond functionalization methods in which we could apply our knowledge on the C–H bond cleavage and apply it to the formation of new scaffolds. The development of two new palladium-catalyzed methods were also described. In the fifth chapter, our effort toward the development of ligands to specifically promoted C–H bond cleavage will be presented. In the sixth chapter will be presented the latest results on the study of the mechanism of the C–H bond cleavage combining experimental and computational studies. In part B of this thesis will be presented our strategy toward the total synthesis of ginkgolide C that included two gold(I)-catalyzed reactions as key steps in the preparation of the spiro[4.4]nonane core of this natural product. The first studies on the feasibility of the key steps of the synthesis will be described.

The development of a novel palladium-catalyzed domino reaction with indole-based gem-dibromoolefin substrates is described. The reaction allowed access to a new class of polycyclic nitrogen heterocycles: N-fused benzo[c]carbazoles. A key feature of this domino reaction was the participation of both bromides in C–H functionalization processes, a hitherto unprecedented reactivity. Various substituents and substitution patterns were tolerated in this reaction, allowing for a highly modular approach to these challenging synthetic targets. Mechanistic studies were performed to gain further insight into the reactivity of these systems and elucidate the sequence of reaction steps. The results indicate that isomerization of reaction intermediates likely played a key role in promoting a successful reaction.

The development of a novel palladium-catalyzed domino reaction with indole-based gem-dibromoolefin substrates is described. The reaction allowed access to a new class of polycyclic nitrogen heterocycles: N-fused benzo[c]carbazoles. A key feature of this domino reaction was the participation of both bromides in C–H functionalization processes, a hitherto unprecedented reactivity. Various substituents and substitution patterns were tolerated in this reaction, allowing for a highly modular approach to these challenging synthetic targets. Mechanistic studies were performed to gain further insight into the reactivity of these systems and elucidate the sequence of reaction steps. The results indicate that isomerization of reaction intermediates likely played a key role in promoting a successful reaction.

The field of metal-catalyzed C–H bond functionalizations is an incredibly vibrant and spans beyond the formations of biaryl motifs. The introduction chapter will cover the mechanistic aspects of the C–H bond functionalization with metal-carboxylate complexes. The mechanistic facets of this reaction will be the main conducting line between the different sections and chapters of the first part of this thesis. In the second chapter, will be described additives that can readily promoted C–H bond arylation of poorly reactive substrates. More specifically, we will revisit the intramolecular direct arylation reaction we will demonstrate the effect of pivalic acid as a co-catalyst by developing milder reaction conditions. In the third chapter we be described experimental and computational studies which suggested that the a single pathway might be involved in the palladium-catalyzed C–H bond functionalization of a wide range of (hetero)arene. Following this we will describe a general set of conditions for the direct arylation of wide range of heteroarenes. Also, we will present two different strategies to selectively and predictably arylate substrates containing multiple functionalizable C–H bonds. In the fourth chapter will be presented our efforts toward the development of new C–H bond functionalization methods in which we could apply our knowledge on the C–H bond cleavage and apply it to the formation of new scaffolds. The development of two new palladium-catalyzed methods were also described. In the fifth chapter, our effort toward the development of ligands to specifically promoted C–H bond cleavage will be presented. In the sixth chapter will be presented the latest results on the study of the mechanism of the C–H bond cleavage combining experimental and computational studies. In part B of this thesis will be presented our strategy toward the total synthesis of ginkgolide C that included two gold(I)-catalyzed reactions as key steps in the preparation of the spiro[4.4]nonane core of this natural product. The first studies on the feasibility of the key steps of the synthesis will be described.

An effiecient stoichiometric amount system has been developed for the synthesis of N-phenylpyridin-2-amine Palladacycle, and then reation with aryl trifluoroborate to 9-(pyridine-2-yl)-9H-carbazoles by C-H bond activation/ C-C bond formation and C-N bond formation. The subsitutent effect of the aryl trifluoroborate with N-phenylpyridin-2-amine Palladacycle intermediate was observed. Mechanistic studies of C-H bond cleavaged, including trapping of reaction intermediates and kinetic isotope effect experiments, are also presented.

Reactions of Fullerene with Tris(diphenylacetylene)(carbonyl)Tungsten and structure identified of these compounds. Due to its have many special mechanism for Tris(diphenylacetylene)(carbonyl)Tungsten. They could form interested structure of new compounds. Synthesis in high temperature we could get metallofullerene compounds W(CO)(£b2-C60)(£b2-PhC¡ÝCPh)(£b4-C4Ph4) 1a and W(CO)(£b2-C60)(¡ÝCPh)(£b5-C5Ph5) 1b. We also through C-H activation to get compound W(CO)2(£b3,£b5-C5Ph4(o-C6H4)CHPh) 2. To separate and Purify these compounds. To make sure mechanism of compound 2, we use cross experiment to confirm it.

The pyrrole-imidazole alkaloid family of natural products illustrates the diversity of topographically unique molecules with potent biological activities that can be found in the marine environment. Thus, great interest for this class of compounds has developed leading to new synthetic methodologies and tactics to build these complex secondary metabolites. The overall objectives of this research project include the total synthesis of the phakellins and phakellstatins. First, we revisited the strategy developed in our group for the total synthesis of (+)-dibromophakellstatin and utilized it for the synthesis of its naturally occurring enantiomer and congeners. Second, we proposed and studied a new and more concise approach to the phakellstatins and phakellins based on a key C-H insertion process developed by Du Bois. Attempts to streamline the first synthesis of (+)-dibromophakellstatin proved to be quite challenging. Shortcomings in the reproducibility of some parts of the original strategy precluded us from completing and making more efficient the synthesis of the natural enantiomer (-)-dibromophakellstatin. Fortuitously, our second generation approach though it presented itself as an efficient route to the phakellins and phakellstatins produced the undesired anti diastereomer of the key guanidine intermediate which precluded our study of the pivotal C-H insertion reaction.

No description available.

The products of vanadium metal atom reactions with propene and some propene isotopomers (propene-d6 and propene-3,3,3-d3) are investigated using FT-IR matrix isolation. The major product from the condensation of V atoms with propene at elevated mole ratios is found to be propane (C3H8), the production of which is seen to increase as concentration of propene increases. Additionally a matrix isolated product formed after metal atom insertion into the C-H bond of propene at low propene mole ratios is isolated and identified. The location of the insertion site is identified as one of the methyl hydrogen carbon bonds. The structure of the product is identified as an allyl vanadium hydride complex, through a FT-IR matrix isolation study of propene isotopomers. It is also shown that this primary product acts as an intermediate in the formation of propane. A full mechanism for the proposed formation of propane from sacrificial hydrogenation is proposed and compared with the reported mechanism for the similar reaction involving ethene. The mechanistic identification of the hydrogenation of propene is shown as a generalization of the previous reaction involving ethene. Photochemistry of reactants and intermediates trapped in the matrix are investigated. Irradiation of matrices with several different UV-visible wavelength ranges indicate that no further chemistry occurs after formation of the matrix and further irradiation has no effect on intermediates or reactants. Additionally the reactivity of water with vanadium and propene under low propene concentration conditions is also studied. Results from this study show that under all conditions studied no incorporation of water into the propene molecule is found. / Thesis (Master, Chemistry) -- Queen's University, 2009-08-10 11:15:55.312