Le motif biaryl contenant la pyridine représente une structure omniprésente dans la chimie organique et médicinale. Ainsi, le développement de méthodes fiables de synthèse est continuellement désiré. Traditionnellement, les cycles azotés biarylés sont efficacement synthétisés par des réactions de couplage croisé catalytique. Cependant, la pyridine peut être difficilement fonctionnalisée en position C-2 compte tenu de sa déficience en électrons. Cette propriété limite son utilisation en tant que partenaire nucléophile dans les réactions de couplage croisé. Par exemple, dans le couplage de Suzuki-Miyaura, l’acide 2-pyridyle boronique est connu pour son instabilité. À l’inverse, les organométalliques du 2-pyridyle sont peu réactifs pour faire des réactions de substitution aromatique électrophile. La synthèse des pyridines 2-substituées est par conséquent un défi qui reste difficile à relever. La première partie de ce mémoire est consacrée au développement récent des méthodes pour résoudre les problèmes de couplage avec des nucléophiles 2-pyridyles. En particulier, les approches classiques comme le couplage modifié de Suzuki-Miyaura, l’activation de liaison C-H des composés pyridinium N-activés, et l’arylation directe du cycle pyridine sont présentées. De plus, les approches alternatives qui utilisent la partie pyridine comme partenaire électrophile dans la réaction couplage avec les réactifs organométalliques sont également discutées. Dans la deuxième partie de ce mémoire, une méthode de couplage croisée entre des esters de sulfonate de 2-pyridyles et des organolithiens est rapportée. Une variété de pyridines 2-substituées a été synthétisées avec succès en faisant réagir des sulfonates de pyridine avec des organolithiens (aryl, alkane, heteroaryle lithium) à basse température. La méthode permet également de s’affranchir de l’utilisation d’un quelconque métal de transition. Des études mécanistiques montrent que le processus impliquant les composés lithiés s’apparente à une réaction de substitution nucléophile aromatique. Cependant, le mécanisme diffère lorsque la réaction met en jeu des réactifs de Grignard, où un processus de couplage entre deux ligands d’un intermédiaire σ-sulfurane peut être impliqué. / Biaryl compounds containing the pyridine moiety represent a ubiquitous structure in both organic and medicinal chemistry. Therefore, finding new and reliable approaches for their synthesis is still of interest. Traditionally, azine containing biaryls are efficiently synthesized via transition-metal catalyzed cross-coupling reactions. However, due to its π-deficient nature, pyridine cannot be easily functionalized at the C-2 position to serve as nucleophile partner. For examples, in the Suzuki-Miyaura cross-coupling reaction, 2-pyridyl boronates are well known for their instability. 2-Pyridyl organometallics undergo electrophilic aromatic substitution poorly. Thus, the synthesis of 2-substituted pyridines remains a challenging task. The first part of the thesis focuses on the recent methods to address the coupling issues of 2-pyridyl nucleophiles in cross-coupling reactions. Of note, the classical methods including Suzuki-Miyaura cross-coupling reactions, C-H activation of N-activated pyridinium species, and direct coupling reaction of pyridine are presented. Alternative approaches using the pyridine moiety as an electrophilic entity in the coupling with organometallic reagents are also discussed. In the second part of the thesis, a transition metal-free desulfinative cross-coupling reaction of 2-pyridyl sulfonates with organolithium reagents is reported. A variety of 2-substituted pyridines were successfully synthesized in good yields, by treatment of neopentyl 2-pyridyl sulfonates and phenyl 2-pyridyl sulfonate with aryl, alkyl, and heteroaryl-lithium reagents at low temperature. Mechanistic studies showed that the coupling reaction with lithium reagents undergoes an SNAr pathway. However, a ligand coupling process of a σ-sulfurane intermediate may be involved in the reaction with Grignard reagents to form the biaryl.

Ce travail est en relation avec la thématique "Energies Propres". Le diméthoxyméthane estun composé adapté au stockage de l’hydrogène pour des applications mobiles, de par saforte teneur en hydrogène, sa très faible toxicité et son faible impact sur l'environnement.De ce fait, des catalyseurs mixtes, à base d’oxyde de vanadium et d’oxyde de titanesulfatés ont été préparés et testés dans la réaction d'oxydation sélective du méthanol enDMM, en vue de la production d'hydrogène. Les propriétés acides et redox de surface ontété corrélées aux performances catalytiques. Les mécanismes de réaction et l'identificationdes facteurs limitant l'activité et la sélectivité des catalyseurs ont été aussi étudiés. / This work is related to the subject “Clean Energy”. Dimethoxymethane (DMM) is asuitable H2 storage material for mobile application because of its high content of hydrogen,extremely low toxicity and environmentally benign. Therefore, sulfated vanadia-titania,sulfated binary vanadia-based and titania-based catalysts were prepared and evaluated inthe reaction of selective oxidation of methanol to DMM and further production ofhydrogen. The surface acidic and redox properties of the studied catalysts were correlatedto their catalytic performance. In addition, the reaction mechanisms and the identificationof factors limiting the activity and selectivity of catalysts were also studied.

La compréhension de l'irradiation à l'échelle du nanomètre dans les systèmes biomoléculaires nécessite l'observation de caractéristiques nouvelles auxquelles les développements techniques actuels nous permettent d'accéder. Ce travail se situe au coeur de la construction du nouveau dispositif DIAM Dispositif d’Irradiation d’Agrégats de Molécules biologiques développé à l’Institut de Physique Nucléaire de Lyon. Le développement d’une source d’agrégats associée à un spectromètre de masse à double focalisation a permis l’obtention des premiers faisceaux d’agrégats moléculaires protonés sélectionnés en masse. De plus, un système de détection innovant a été développé et validé dans des expériences de dissociations d’agrégats d’eau protonés par collision sur un gaz. Les résultats obtenus contribuent à la connaissance de la stabilité et de la structure des petits agrégats d’eau protonés et des agrégats mixtes d’eau et de pyridine protonés / Nanoscale characterization of irradiation in biomolecular systems requires observation of novel features which are now achievable with the recent technical progress. This work is a central part in the development of DIAM which is a new experimental set-up devoted to irradiation of biomolecular clusters at the Institut de Physique Nucléaire de Lyon. The development of the cluster source and of a double focusing mass spectrometer leads to the production of intense beams of mass selected protonated molecular clusters. Combined with this mass selected cluster beams an innovative detection technique is demonstrated in collision induced dissociation experiments. The results contribute to the knowledge of the stability and the structure of the small protonated water clusters and mixed clusters of water and pyridine

This diploma thesis focuses on possibilities of applications of UV radiation to remove pollutants from water. It summarizes sources of UV radiation and list their benefits and properties. The thesis characterizes so called advanced oxidation processes using UV light. Degradation pathways od pyridine and its derivatives especially halogenated pyridines are described. The photodegradability of pyridine and a rate of this reaction in model water is investigated in the experimental part. Also, the effect of concentration and dose of H2O2 is assessed. Gas chromatography was used to determinate concentrations of pyridine in samples.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

The activation parameters for the temperature dependent irreversible loss of surface-enhanced Raman scattered (SERS) intensity from pyridine and chloride adsorbed at silver surfaces in an electrochemical environment have been determined. Laser-induced heating is introduced as a probe of the chemical nature of SERS-active sites. Surface temperatures are calculated from spectroscopic data. The activation energies associated with the destruction of SERS-active sites at a surface roughened by an illuminated oxidation-reduction cycle (ORC) are 12.8 ± 3.2 kcal/mole and 27.7 ± 3.1 kcal/mole for pyridine at two different types of sites on the Ag surface. Similarly, values for coadsorbed chloride are found to be 11.1 ± 2.4 kcal/mole and 24.5 ± 3.8 kcal/mole. An activation energy of 27.4 ± 1.9 kcal/mole is obtained for pyridine on a silver surface roughened by a nonilluminated ORC. Evidence for the desorption of pyridine and chloride is presented.

This work was initially launched to study the synthesis of low-valent group 13 compounds bearing the bis(imino)pyridine ligand framework. Since its inception, this project has grown beyond the boundaries of group 13 to include low valent tin, silver, and rhenium. Alongside the reports of novel coordination compounds, we utilized computational chemistry to uncover unprecedented interactions which challenge conventional concepts of bonding. Synthesis, characterization, and complimentary computational studies are presented herein. Chapter 1 presents a historical overview of the bis(imino)pyridine ligand as well as our synthetic methodology and characterization of new ligand variants we have contributed to the literature. Chapter 2 presents the synthesis of a series of In(I) and In(III) bis(imino)pyridine complexes with varied sterics. Ligand-metal interaction and effect of ligand steric bulk on complex stability, as well as computational studies highlighting weak covalent interactions will be discussed. Chapter 3 presents the synthesis of Ga(III) bis(imino)pyridine complexes. Reactivity with “GaI” synthon as well as varied-stoichiometry one-pot synthesis attempts to generate low valent Ga-bis(imino)pyridine complexes will be discussed. Chapter 4 presents the synthesis of a series of Tl(I) bis(imino)pyridine complexes with varied sterics analogous to the approach taken with indium(I). Unprecedented weak ligand-metal as well as Tl-arene interactions will be discussed. Chapter 5 presents the synthesis of a series of Sn(II) bis(imino)pyridine complexes with varied sterics and halide substituents. Preferential cation-anion pair formation and attempted reactivity will be discussed. Chapter 6 presents the synthesis of a series of Ag(I) bis(imino)pyridine complexes with varied sterics. Resulting ligand-metal interactions as well as reactivity towards Lewis basic donor ligands will be discussed. Chapter 7 presents the synthesis of first crystallographically authenticated examples of rhenium(I) pincer complexes utilizing the bis(imino)pyridine ligand. Chapter 8 presents a general conclusion to the work.

Le travail décrit dans ce mémoire concerne l'étude de la métallation régiosélective de deux bicycles fusionnés complexes : les furo[3,2-b]- et [2,3-c]pyridines. L'influence de la nature du système basique sur le cours de la réaction et sur la régiosélectivité de la lithiation a été étudiée avec différentes bases : n-BuLi, LTMP, LDA et [n-BuLi/LiDMAE]. D'un point de vue fondamental, cette étude nous a permis d'établir quelques règles pour la fonctionnalisation des hétérocycles complexes, ce qui nous a conduit à l'obtention efficace et rapide d'une vaste chimiothèque de furo[3,2-b]- et [2,3-c]pyridines polyfonctionnalisés et refonctionnalisables. Quelques composés préparés ont ainsi été mis en jeu dans des réactions de couplage catalysées par les métaux de transition (Pd, Ni). Les difficultés rencontrées au cours de ce travail nous ont permises de mettre en évidence une séquence de double fonctionnalisation des hétérocycles ?-déficients par une séquence "one-pot" combinant le piégeage d'un intermédiaire lithié par un électrophile et l'addition nucléophile d'une espèce réactive générée in-situ. Le développement de cette séquence nous a conduits à l'obtention directe de pyrazines, pyridines et furo[3,2-b]pyridines disubstituées / The work described in this PhD thesis concerns a regioselective metalation study of two fused heterocycles : the furo[3,2-b]- et [2,3-c]pyridines. The influence of the lithiated agent on the reaction course and on the selectivity of the lithiation has been studied with several bases : n-BuLi, LTMP, LDA and [n-BuLi/LiDMAE]. From a fundamental point of view, this study allowed us to establish some rules concerning the functionalisation of fused heterocycles, and then, a chemical library of polyfunctionalised furo[3,2-b]- and [2,3-c]pyridines has been designed. Some of the compounds obtained in this way were engaged in metallo-catalysed coupling reactions. The difficulties we met during this work allowed us to discover a double functionalisation sequence of ?-deficient heterocycles via a cascade process combining the trapping of lithiated intermediates and the nucleophilic addition of some in-situ released species. The development of this sequence afforded direct access to difunctionalised pyrazines, pyridines and furo[3,2-b]pyridines

The levels of total nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), and their redox states were determined as the function of growth in S. cerevisiae. Cells growing in a medium containing 0.8% glucose exhibit two phases of exponential growth, utilizing glucose and ethanol, respectively. The NAD pool is 50% reduced during both stages of growth while the NADP pool is 67% reduced in glucose growth and 48% reduced in ethanol growth. The NAD/NADP ratio is constant during growth on glucose and a two-fold increase in the NAD/NADP ratio occurs upon exhaustion of glucose. The increased ratio is maintained during growth on ethanol. This alteration in the regulation of the relative levels of NAD and NADP may be due to a change in the regulation of NAD kinase and/or NADP phosphatase activities. These changes may be related to the redox state of the NADP pool.

M.Sc. / 2-(Pyrazol-1-ylmethyl)pyridine ligands were synthesised by phase transfer alkylation of 2-picolyl hydrochloride with the appropriate pyrazole. These ligands were subsequently reacted with NiCl2, NiBr2, FeCl2 or CoCl2 to form the respective complexes. The substituents on the pyrazole included phenyl and tert-butyl groups as well as electron withdrawing CF3 groups. The substituents played an important role in the steric and electrophilic nature of the metals. A second ligand design is 2,6-bis(pyrazol-1-ylmethyl)pyridine and were prepared by phase transfer alkylation of 2,6-bis(chloromethyl)pyridine with two mole equivalents of the appropriate pyrazole. These ligands were reacted with NiCl2, NiBr2, FeCl2 or CoCl2 to form the respective complexes. A third ligand design is 2-(chloromethyl)- or 2-(bromomethyl)-6-(pyrazol-1-ylmethyl)pyridine and were prepared by the selective alkylation of 2,6-bis(chloromethyl)pyridine with one mole equivalent of the appropriate pyrazole. These ligands were also reacted with NiCl2, NiBr2, FeCl2 or CoCl2 to form the respective complexes. Characterisation of all compounds was done by a range of spectroscopic techniques as well as X-ray crystallography and elemental analysis. The data showed good fit to the proposed structures and in a few cases were confirmed by X-Ray crystallography. All complexes were tested as catalysts for ethylene and higher olefin oligomerisation and showed good activity. The production of alkenes were confirmed in toluene and hexane, however, due to the use of EtAlCl2 and toluene the oligomers were alkylated to form the Friedel-Crafts alkylation products. Similar alkylation was observed for the higher olefin reactions. In comparison, the same reactions in hexane resulted in only C4, C6 and C8 oligomers. When higher olefin reactions were also conducted in hexane, polymeric solids were observed.