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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Palladium-Catalyzed Carbonylation and Arylation Reactions

Sävmarker, Jonas January 2012 (has links)
Palladium-catalyzed reactions have found widespread use in contemporary organic chemistry due to their impressive range of functional group tolerance and high chemo- and regioselectivity. The pioneering contributions to the development of the Pd-catalyzed C-C bond forming cross-coupling reaction were rewarded with the Nobel Prize in Chemistry in 2010. Today, this is a rapidly growing field, and the development of novel methods, as well as the theoretical understanding of the various processes involved are of immense importance for continued progress in this field. The aim of the work presented in this thesis was to develop novel palladium(0)- and palladium(II)-catalyzed reactions. The work involved in achieving this aim led to the development of a Mo(CO)6-mediated carbonylative Stille cross coupling reaction for the preparation of various deoxybenzoins. The protocol utilized convenient gas-free conditions to facilitate the carbonylative coupling of benzyl bromides and chlorides with aryl and heteroaryl stannanes. Mo(CO)6-assisted conditions were then used in the development of a general protocol suitable for the aminocarbonylation of aryl triflates. Both electron-poor and electron-rich triflates were coupled with primary, secondary and aryl amines. In addition, DMAP was found to be a beneficial additive when using sterically hindered or poorly nucleophilic amines. An efficient and convenient method for the synthesis of styrenes from arylboranes was developed, employing the relatively inexpensive vinyl acetate as the ethene source under Pd(II)-catalyzed conditions. The reaction mechanism was studied using ESI-MS, and a plausible catalytic cycle was proposed. A method for the oxidative Heck reaction employing aryltrifluoroborates and aryl MIDA boronates was also developed. Electron-rich and electron-poor olefins were regioselectively arylated under microwave-assisted conditions. Various arylboron species were identified in an ongoing reaction using ESI-MS.    Further investigations led to the development of a direct method for the synthesis of arylamidines from aryltrifluoroborates and cyanamides. Under Pd(II)-catalyzed conditions it was possible to insert the aryl into primary, secondary and tertiary cyanamides. Finally, a desulfitative method for the synthesis of aryl ketones was developed. A variety of aryl sulfinates were effectively inserted into alkyl- and aryl nitriles. The mechanism was further investigated using ESI-MS and a plausible catalytic cycle was proposed.
32

Mechanisms of regulation of dioxin receptor function /

Lindebro, Maria, January 2002 (has links)
Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 3 uppsatser.
33

Functional role of a constitutively active dioxin/Ah receptor in a transgenic mouse model /

Andersson, Patrik, January 2003 (has links)
Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 4 uppsatser.
34

Synthesis of indoles, bisindoles and indolocarbazoles : high affinity aryl hydrocarbon receptor ligands /

Wahlström, Niklas, January 2004 (has links)
Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 6 uppsatser.
35

CYP2C9 binding determinants and activation mechanisms for phenytoin and (S)-warfarin metabolism /

Mosher, Carrie M. January 2008 (has links)
Thesis (Ph. D.)--University of Washington, 2008. / Vita. Includes bibliographical references (leaves 186-207).
36

Dynamic regulation of aryl hydrocarbon receptor function and activity by different stimuli

Lücke, Sandra, January 2010 (has links)
Diss. (sammanfattning) Stockholm : Karolinska institutet, 2010.
37

Syntheses and catalytic properties of palladium (II) complexes of various new aryl and aryl alkyl phosphane ligands

Vuoti, S. (Sauli) 27 November 2007 (has links)
Abstract Thirty three aryl and aryl alkyl phosphane ligands were prepared and characterized for catalytic purposes. The aryl groups in both types of ligands were modified with alkyl substituents (methyl, ethyl, isopropyl, cyclohexyl, phenyl) or hetero substituents (methoxy, N,N-dimethylaniline, thiomethyl). The alkyl groups directly attached to the phosphorous atom were ethyl, isopropyl or cyclohexyl. Mono- and in some cases also dinuclear palladium (II) complexes of the ligands were prepared and characterized. The syntheses of the palladium complexes are solvent-dependent and afford either mono- or dinuclear complexes depending on the choice of the solvent. Additionally, two 2-mercaptobenzothiazole palladium complexes were synthesized and characterized. A rare distorted lantern-type structure was presented for the first time. The ligands were characterized by 1H, 13C, 31P NMR spectroscopy and mass spectrometry. The palladium complexes were characterized by 31P NMR spectroscopy, X-ray crystallography and elemental analysis. Links between the NMR data of the palladium complexes and ligands and their catalytic activity was screened and correlation found. The crystal structures of the palladium complexes were studied for possible attractive interactions between two ligands. Such interactions were found from two examples. There is an attractive interaction between the phenyl and quinolinyl moieties of 2-quinolinyldiphenyl phosphane. A similar interaction was found between the methyl substitute and phenyl ring of o-tolylphosphane. The ligands and palladium complexes presented in this thesis were prepared in hope of finding suitable catalysts for Suzuki coupling reactions of various bulky aryl halides and phenyl boronic acids to prepare sterically hindered bi- and triaryls under microwave irradiation. A selection of aryl alkyl phosphane ligands catalyzed the couplings of bulky aryl bromides and even unactivated aryl chlorides efficiently and produced high yields. The reaction conditions of a new catalyst system were optimized, and it was noticed that the addition of a small amount of water enhanced the purity and yield of the coupling products further.
38

Aryl Hydrocarbon Hydroxylase and Sixteen Alpha Hydroxylase in Cultured Human Lymphocytes

Coomes, Marguerite L. 12 1900 (has links)
Cultured human lymphocytes may be assayed for aryl hydrocarbon hydroxylase (AHH) in whole cell preparations. The optimum assay conditions are pH 8.5, and 1.5 mM Mg++. The reaction is linear with time and cell number, and is inhibited by CO. Estradiol may inhibit induction of AHH by 3-methylcholanthrene, but is a poor competitor for the enzyme. A Caucasian population was assayed for AHH activity. The distribution was lognormal; no difference was found in cultured cells from males and females or smokers and nonsmokers. Cells from relatives of lung cancer patients showed higher activity. An American Indian population showed no difference from the Caucasian population in enzyme level. No linkage was found between AHH and 16a-hydroxylase.
39

Isolation, identification and chemical modification of Narcissus alkaloids

Burke, Edmund William Dwerryhouse January 2016 (has links)
Galanthamine is one of only a few drugs that is licenced for the treatment of Alzheimer's disease. It is manufactured through an inefficient synthetic process or extracted from members of the Amaryllidaceae plant family. In this work a range of structurally related alkaloids was semisynthesised from galanthamine and used as standards to assist with the search for alkaloids that may make a good starting point in the semisynthesis of galanthamine. The search was targeted on the effluent from the production line of Alzeim Ltd., a company that extracted galanthamine from members of the Narcissus genus. In addition to the above there was an examination of specific areas of galanthamine chemistry; focusing on the application of synthetic methodologies to open new chemical space. By far the most successful of these was the use of galanthamine in a urea-mediated intramolecular aryl migration. A rare example of lithiation chemistry being applied to a natural product and also the most complicated structure to date on which the intramolecular aryl migration has been performed.
40

Hydrogen-bonding and halogen-arene interactions

Dominelli Whiteley, Nicholas January 2017 (has links)
Non-covalent interactions are fundamental to molecular recognition processes that underpin the structure and function of chemical and biological systems. Their study is often difficult due to the interplay of multiple interactions and solvent effects common in complex systems. Herein, chapter one provides some general background on the area before presenting a literature review of key, contemporary developments on the use of folding molecules for the quantification of non-covalent interactions. Chapter two investigates the magnitude and extent of energetic cooperativity in H-bond chains. Utilising supramolecular complexes and synthetic molecular torsion balances, direct measurements of energetic cooperativity are presented in an experimental system in which the geometry and number of H-bonds in a chain were systematically controlled. Strikingly, it was found that adding a second H-bond donor to form a chain can almost double the strength of the terminal H-bond, while further extension had very little effect. Computations provide insights into this strong, short-range cooperative effect in a range of H-bonding contexts. Chapters three and four build on the concepts and molecular models discussed in chapter two. Chapter three discusses the effects of interplay and competition between strong H-bond acceptors such as formyl groups and the weaker organofluorine H-bond acceptor. There has been some debate in recent literature about the latter’s ability to accept H-bonds, the work presented shows that although organofluorine is a weak H-bond acceptor, it can have a significant modulating effect on stronger interactions when in direct competition. Chapter four investigates deuterium isotope effects on conformational equilibria governed by non-covalent interactions. The results show that any deuterium isotope effect which exists is less than the margins of experimental error. Finally, chapter five discusses a molecular torsion balance designed to investigate halogen∙∙∙arene interactions. The interaction energies were investigated in a range of solvents and mixtures in order to dissect out the dispersive and solvophobic components of folding. Overall, these interactions were found to be weak. Nonetheless, a model was used to dissect trends in solvophobic and electronic contributions to the binding using multiple linear regression based upon the cohesive energy density and polarisabilities of the solvents.

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