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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.
81

Total synthesis of lavendamycin analogs

Stocksdale, Mark G. January 1992 (has links)
The syntheses of 7-N-chloroacetyllavendamycin methyl ester (55), 7-N-butyryllavendamycin methyl ester (56), 7-N-chloroacetyldemethyllavendamycin octyl ester (57), 7-N-butyryldemethyllavendamycin octyl ester (58), 7-N-chloroacetyldemethyllavendamycin isoamyl ester (59), and 7-N-butyryldemethyllavendamycin isoamyl ester (61) are described. Incorporation of the Pictet-Spengler condensation of 7-chloroacetamido-2-formylquinoline-5,8-dione (62) or 7butyramido-2-formylquinoline-5,8-dione (63) with B - methyltryptophan methyl ester (11), L-tryptophan octyl ester (64), or L-tryptophan isoamyl ester (65) in xylene directly afforded six lavendamycin analogs.The aldehydes 62 and 63 were prepared according to the following general procedure. Nitration of 8-hydroxy-2methylquinoline (66) yielded 8-hydroxy-2-methyl-5,772, and 73 are also included. 1H NMR and IR are provided compounds 67, and 71, and 1H NMR is provided for compound dinitroquinoline (67). Compound 67 was then hydrogenated and acylated with chloroacetic anhydride (or butyric anhydride) to yield 5,7-bis(chloroacet4mido)-8-hydroxy-2-methylquinoline (69) (or 5,7-dibutyramido-8-butyroxy-2 methylquinoline (71)).Compound 69 (and 71) was oxidized by potassium dichromate to give the corresponding 5,8-dione 70 (and 72). Treatment of 70 (and 72) with selenium dioxide in refluxing 1,4-dioxane afforded compound 62 (and 63). It was also noted that 71 would hydrolyze to its 8-hydroxy derivative 73 in hot methanol-water.Compound 64 was prepared through the neutralization of Ltryptophan octyl ester hydrochloride with a 14 % ammonium hydroxide solution followed by extraction. Compound 65 was synthesized via a Fischer esterification of L-tryptophan with isoamyl alcohol saturated with hydrogen chloride. The synthesis of H-methyltryptophan (44) was accomplished with the method of Snyder and Matteson.The structures of the novel compounds 55, 56, 57, 58, 59, 60, 62, 63, 69, 70, 72 and 73 were confirmed through 1H NMR, IR, EIMS, and HRMS. Elemental analyses of 62, 63, 69, 70,for 44. / Department of Chemistry
82

Novel synthesis of quinoline-5,8-dione analogues

Teitgen, Alicen M. 21 July 2012 (has links)
The chemistry of quinonline-5,8-dione as a functional group is a developing field because of its various biological aspects. Lavendamycin and streptonigrin are known antibiotic, antitumor agents containing the quinolone-5,8-dione functional group believed to provide their antitumor properties. Most cancer cells show an elevated level of NQO1 enzyme which activates lavendamycin to act as an antitumor agent. The research goal is to explore different synthetic methods and reactions to produce novel quinolone-5,8-dione analogues with unique structural features while keeping the selective cytotoxicity. Lavendamycin contains a β-carboline and streptonigrin has a substituted pyridine connected to the 2-position of the quinolone-5,8-dione. The overall goal of this project will develop synthetic methods to create 1,2,3-triazoles and 1,2-diazoles attached to the quinoline moiety from azides and diazonium salts, respectively. In order to accomplish this, 8-hydroxyquinoline undergoes through a four step synthesis to install an azide at the two position of the quinoline ring. 8-Hydroxyquinoline was oxidized to produce 8-hydroxyquinoline-N-oxide, converted into 8-acetoxy-2-hydroxyquinoline with acetic anhydride, reacted with POCl3 to produce 2-chloro-8-hydroxyquinoline, and treated with sodium azide to form 2-azido-8-hydroxyquinoline. However it was found that the product cyclized to yield 8-hydroxy-tetrazole[1,5-a]quinoline. In the quinoline-5,8-dione synthesis, 7-amidoquinoline-5,8-dione is prepared through a three step synthesis. 8-Hydroxquinoline was nitrated to form 8-hydroxy-5,7-dinitroquinoline, hydrogenated/acylated to give 5,7-diacetamido-8-acetoxyquinoline, and oxidized to yield 7-acetamidoquinoline-5,8-dione. In order to reach the end of this project, the four step tetrazole and the three step quinoline-5,8-dione syntheses required merging. Further research will focus on the optimization of these syntheses. / Synthesis of 8-hydroxy-tetrazole [1,5-a] quinoline -- Synthesis of 7-amino-quinoline-5,8-dione -- Novel synthesis of quinoline-5,8-dione analogues. / Department of Chemistry
83

Synthetic approaches to functionalised piperidines

Woods, Gordon Alexander January 1999 (has links)
This thesis is concerned with the synthesis of functionalised piperidines. The piperidine unit is found in numerous alkaloids and other natural products, and has also been incorporated into synthetic compounds of significant therapeutic or strategic synthetic potential. Although numerous syntheses of individual piperidine compounds have been published, there are few general routes to this class of compounds, and there is therefore a need for such routes to be developed. Bicyclic lactams derived from (S)-pyroglutamic acid have been shown to be useful synthons in the synthesis of pyrrolidines. An analogous bicyclic lactam was therefore synthesised from (S)-lysine. Alkylations at the carbon atom a- to the lactam carbonyl group were studied in detail. A number of different groups could be introduced in good to excellent yield, and with moderate to good stereoselectivity. The selectivity of these reactions was believed to depend on the shape of the bicyclic system, and a stereoelectronic effect of the nitrogen lone pair. The bicyclic lactam was further elaborated to an activated enone. This was shown to be relatively unreactive to cycloaddition reactions. It is believed that this is because the activating ester group is not conjugated with the carbon-carbon double bond. However, conjugate addition could be achieved in high yield and excellent stereoselectivity using a zinc enolate Reformatsky reagent. An epoxide could also be formed in excellent yield and with excellent stereoselectivity. The Reformatsky adduct was shown to be a suitable substrate for a Pb(IV)-mediated arylation reaction. Examples of the functionalised lactams were deprotected to give hydroxymethyl piperidinones and cyclic amino acids. This route therefore allows access to the desired novel compounds.
84

Structure-reactivity relationships through X-ray and neutron diffraction studies

Wilson, Claire January 1995 (has links)
This thesis is primarily concerned with the investigation of a structure-reactivity relationship in a series of pentacyclic Isodrin derivatives. These compounds undergo a two-hydrogen atom dyotropic rearrangement at vastly differing rates when apparently small structural changes are made. Two pairs of these isomers (with the formulas C(_16)H(_8)Cl(_10) and C(_16)H(_9)Cl(_9) ) have been investigated using both X-ray and neutron single crystal diffraction studies, at ambient and low temperatures. The experimental details of these studies are given for five experiments and the results of the least-squares refinements made using the data from these experiments are reported herein. In addition to conventional crystallographic studies, an experimental charge density study of one of these compounds, C(_16)H(_9)Cl(_9), has been made at 123K. The electron density was modelled using a multipole model which allows explicitly for the aspherical nature of the electron density. The results of this study, including a topological analysis of the charge density are reported in this thesis. The structures of six organometallic, four molybdenum bis(imido) and two half-sandwich niobium imido complexes, are also reported herein. Their structures were determined from single crystal diffraction data. These compounds show the expected structures predicted using the pseudo-isolobal relationship to the Group 4 bent metallocenes of which they may be considered analogues.
85

A study of 1,3-dipolar cycloadditions as a route to novel pesticides

Farouk, Sultan January 1994 (has links)
No description available.
86

The Distribution of Values of Logarithmic Derivatives of Real L-functions

Mourtada, Mariam Mohamad 09 August 2013 (has links)
We prove in this thesis three main results, involving the distribution of values of $L'/L(\sigma,\chi_D)$,$D$ being a fundamental discriminant, and $\chi_D$ the real character attached to it. We prove two Omega theorems for $L'/L(1,\chi_D)$, compute the moments of $L'/L(1,\chi_D)$, and construct under GRH, for each $\sigma>1/2$,a density function ${\cal Q}_\sigma$ such that \[\#\{D ~~\text{fundamental discriminants, such that}~~ |D|\leq Y,~~ \text{and}~~ \alpha \leq L'/L(\sigma,\chi_D)\leq \beta \} \]\[ \sim \frac{6}{\pi^2\sqrt{2\pi}} Y \int_\alpha^\beta {\cal Q}_\sigma(x)dx . \]
87

The Distribution of Values of Logarithmic Derivatives of Real L-functions

Mourtada, Mariam Mohamad 09 August 2013 (has links)
We prove in this thesis three main results, involving the distribution of values of $L'/L(\sigma,\chi_D)$,$D$ being a fundamental discriminant, and $\chi_D$ the real character attached to it. We prove two Omega theorems for $L'/L(1,\chi_D)$, compute the moments of $L'/L(1,\chi_D)$, and construct under GRH, for each $\sigma>1/2$,a density function ${\cal Q}_\sigma$ such that \[\#\{D ~~\text{fundamental discriminants, such that}~~ |D|\leq Y,~~ \text{and}~~ \alpha \leq L'/L(\sigma,\chi_D)\leq \beta \} \]\[ \sim \frac{6}{\pi^2\sqrt{2\pi}} Y \int_\alpha^\beta {\cal Q}_\sigma(x)dx . \]
88

Pricing derivatives using Gram-Charlier Expansions

Cheng, Yin-Hei 09 April 2013 (has links)
In this thesis, we provide several applications of Gram-Charlier expansions in derivative pricing. We first give an exposition on how to calculate swaption prices under the the CIR2 model. Then we extend this method to CIR2++ model. We also develop a procedure to calculate European call options under Heston’s model of stochastic volatility by Gram-Charlier Expansions.
89

Biologically active natural products: ochromycinone analogues and aurein peptides : a thesis presented for the degree of Doctor of Philosophy / by Tomas Rozek.

Rozek, Tomas January 2000 (has links)
Includes copies of articles co-authored by the author during preparation of this thesis. / Includes bibliographical references (leaves 185-191). / v, 192 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Sixteen aurein peptides are present in the host defence secretion from the granular dorsal glands of the Green and Golden Bell Frog (Litoria aurea) and seventeen from those of the related Southern Bell Frog (Litoria raniformis). All peptides have been sequenced using a combination of electrospray mass spectrometry and Lys-C digestion, with each sequence confirmed by automated Edman sequencing. Ten of these peptides are common to both species of frog. Thirteen of the aurein peptides show wide-spectrum antibiotic and anticancer activity. / Thesis (Ph.D.)--Adelaide University, Dept. of Chemistry, 2001
90

Solvolytic and mass spectral studies of some [omega]-cyclooctatetraenylalkyl derivatives

Mular, Michael January 1974 (has links)
v, 245 leaves ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1974) from the Dept. of Organic Chemistry, University of Adelaide

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