Thesis (doctoral)--Umeå Universitet, Sweden, 1988. / Extra t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis--Universität Heidelberg, 1894.

Thesis (Ph.D.) - University of Queensland, 2006. / Includes bibliography.

The scope of microwave induced synthesis of various cyclic compounds was investigated and considerably expanded. The advantages of this synthetic method were clearly demonstrated when compared to conventional heating methods of organic synthesis. The exposure of organic compounds to continual Ultraviolet (UV) radiation damages the materials and reduces their chemical and physical properties and in most cases irreversibly and this is not only a concern for industry but for consumers as well. Particularly prevalent are incidences of skin cancer now linked to UV radiation. Research efforts are directed towards finding cheap and efficient UV-absorbers to protect such light sensitive materials. Phenyl salicylates and hydroxybenzophenones constitute families of UV-absorber compounds, and this has necessitated this research. The condensation of differently substituted phenols with salicylic acid, catalyzed by either phosphoric acid (PPA), POCl3/ZnCl2 or ZnCl2 afforded the anticipated phenolic type UV -absorber molecules such as phenyl salicylate, 4-hydroxyphenyl-2-hydroxybenzoate, 2,3-dihydroxyphenyl-2-hydroxyphenylbenzoate, 3-hydroxyphenyl-2-hydroxybenzoate, (2,4-dihydroxyphenyl)(2-hydroxyphenyl)methanone, (2,3-dihydroxyphenyl)(2-hydroxyphenyl) methanone and 1,3-dihydroxyxanthone. PPA proved to be a more efficient catalyst for the condensation of salicylic acid with phenol, hydroquinone, pyrogallol and catechol while POCl3/ZnCl2 gave higher yields for resorcinol and phloroglucinol. In all cases, ZnCl2 alone did not show significant yield enhancement. The second part of this research work describes a convenient one-pot synthesis of NMethyl-2-pyrrolidone (NMP) an important industrial solvent by a conventional heating process and by microwave irradiation. The intermediate N-Methyl-hydroxybutyramide formed from the exothermic reaction of =-butyrolactone with aqueous monomethylamine, underwent an intramolecular condensation reaction catalyzed by highly active copper powder to form the anticipated product in very good yields.

The isomers of cyclo(Trp-Pro) (cyclo(L-Trp-L-Pro), cyclo(L-Trp-D-Pro), cyclo(D-Trp-LPro) and cyclo(D-Trp-D-Pro)) have been successfully synthesized and screened for biological activity. High percentage yields were obtained by using the three phase synthesis system, which involves the synthesis of the intermediate protected linear dipeptides, followed by the removal of the protecting Boc groups. This step is followed by cyclization and crystallization of the isomers. The diketopiperazines rings of cyclo(L-Trp-L-Pro) and cyclo(D-Trp-D-Pro) contain cisamide bonds, while cyclo(L-Trp-D-Pro) and cyclo(D-Trp-L-Pro) contain trans-amide bonds. These bonds govern the conformation of the diketopiperazines ring. The isomers have shown different degrees of biological activity, possibly as a result of the orientation of the side chain of tryptophan and this difference in conformation, leading to varying interactions between isomer and a range of receptors. Under experimental conditions, 10-3 M cyclo(L-Trp-D-Pro) and cyclo(D-Trp-L-Pro) showed effective anticancer activity against the cervical cancer cell line, HeLa, resulting in a <50% reduction in cell viability. Cytotoxicity screening with cyclo(D-Trp-L-Pro) indicated that it was hepatocyte-specific in its toxicity, whilst the other isomers were cytotoxic against the other cell types tested. At 1mg/ml, cyclo(L-Trp-L-Pro) proved to be an effective antimicrobial agent against Gram positive bacteria, while cyclo(L-Trp-DPro) effectively inhibited the growth of the Gram negative bacteria, Esherichia coli. Cyclo(D-Trp-L-Pro) proved to be effective against Streptococcus, while cyclo(D-Trp-DPro) effectively reduced viability of the yeast, Candida albicans. Cyclo(D-Trp-L-Pro) was the only isomer to show Ca2+-channel antagonism, whilst the other isomers resulted in opening of the Ca2+-channel. No effects were observed on K+-channel activity for all the isomers tested. The isomers also proved to be valuable antiarrhythmic agents by effectively reducing the time spent in ventricular tachycardia and arrhythmia, as well as decreasing the time for the heart rate to return to a normal sinus rhythm. Furthermore, cyclo(L-Trp-D-Pro) showed positive chronotropic activity, while cyclo(D-Trp-L-Pro) ii showed negative chronotropic activity. In addition, cyclo(L-Trp-D-Pro) and cyclo(D-Trp- L-Pro) also increased the coronary flow rate. 0.125 –1 mM Cyclo(L-Trp-D-Pro) decreased aggregation in washed platelets induced by thrombin. All isomers increased adhesion to an artificial surface when the platelets were stimulated by ADP, yet caused reduced adhesion when the platelets were stimulated by thrombin. These results prove the potential of these compounds as novel agents in a range of biological fields, indicating that a combination of L- and D- amino acids may prove more effective than an agent consisting solely of L-amino acids.

No description available.

The structures of four inorganic compounds have been determined by single-crystal X-ray diffraction methods. Three of the structures investigated were phosphonitrilic derivatives: octamethylcyclotetra-phosphonitrilium trichlorocopper(II), [NPMe₂]₄H.CuCl₃, bis-(octa-methylcyclotetraphosphonitrilium) tetrachlorocobaltate(II), [(NPMe₂)₄H⁺] ₂ CoCl₄²ˉ , and hexadecamethoxycyclo-octaphosphonitrile, [NP(OMe)₂]₈. The fourth analysis was a study of the ionic compound caesium difluorophosphate. For each structure determination the intensity measurements were collected on a diffractometer using a scintillation counter and Mo-K̲⍺ radiation. The structure of [NPMe₂]₄H.CuCl₃ was determined from Patterson and Fourier summations. Refinement of positional and thermal parameters of the atoms was by least squares. The structure consists of discrete molecules in which the eight-member phosphonitrilic ring approximates the "tub" conformation with pairs of adjacent phosphorus and nitrogen atoms displaced alternately above and below the ring plane. A ring nitrogen atom is bonded to the copper atom (N-Cu = 2.04 Å) which has three chlorines arranged about it in a distorted square planar configuration. Across the ring from the N-Cu bond, there is a protonated nitrogen atom which is hydrogen-bonded to a neighbouring chlorine. The phosphorus-nitrogen bond lengths are not equal around the ring, but occur instead in four distinct pairs having lengths 1.63 Å, 1.60 Å, 1.56 Å, and 1.67 Å. These varying bond distances are explainable in terms of π-bonding systems. The structure of [ (NPMe₂)₄H⁺] ₂CoCl₄²ˉ has been determined by Patterson and Fourier methods and refined by least-squares. Most of the methyl hydrogen atoms were located in a final difference Fourier summation. The structure consists of tetrahedral CoCl₄²ˉ ions hydrogen-bonded to two protonated phosphonitrilic rings. The N-H...C1 distance in each case is 3.21 Å. The two independent rings have slightly different conformations. One approaches the "tub" shape and the other tends towards the "saddle" conformation. Protonation of the phosphonitrilic rings again results in non-equivalent P-N bond lengths. Averaged values for the two rings are 1.69 Å, 1.54 Å, 1.61 Å and 1.58 Å. Parameters which are unaffected by the addition of the proton agree with those found in related compounds when averaged values are considered. [NP(OMe)₂]₈ is a centrosymmetric sixteen-member phosphonitrile. Its structure was determined by Patterson, electron density, and least squares techniques. The phosphonitrilic ring consists of two approximately planar and parallel six-atom segments joined by a step. The P-N bond lengths are all equal within experimental error, their mean being 1.561 Å. The average P-0 and 0-C bond distances are 1.576 Å and 1.440 Å respectively. The methoxy groups cover the ring evenly, their arrangement being such that there is little conflict between steric and π- bonding requirements. The structure of caesium difluorophosphate was determined by comparison with KPO₂F₂ and refined by least square methods. Caesium and rubidium difluorophosphate are isomorphous with the potassium salt; all have the barium sulfate structure. The mean P-F distance in CsP0₂F₂ is 1.58 Å, the P-0 bond length, 1.48 Å. The lattice parameters and interionic distances increase with increasing radius of the alkali-metal cation. / Science, Faculty of / Chemistry, Department of / Graduate

The preparation of the β-keto lactones 1̲9̲ via intramolecular alcoholysis of hydroxy Meldrum's acid derivatives was examined. Good yields of the 6- and 14-membered compounds were obtained, but the method was completely unsuccessful for medium-size rings. An investigation was conducted on the conformational preference of substituted 14-merabered lactones with a view to understanding the stereochemical consequences of the reactions of these compounds. The conformational preferences of simple 14-membered cyclic compounds were first determined. These preferences are described in terms of steric and electronic interactions, with the support of computer-calculated steric energies. A number of 14-membered lactones were prepared, beginning with the β-keto lactone 3-oxo-13-tetradecanolide (1̲3̲8̲). Hydride reduction of (1̲3̲8̲) gave the diastereomeric alcohols 1̲4̲6̲ and 1̲4̲7̲, which were then elaborated to give a series of derivatives. The stereochemistry and conformations of these compounds were determined by X-ray crystallography and/or nmr analysis. The preferred conformation was found to be Dale's [3434] diamond lattice model. The relative rates of reaction were determined for several reactions of the alcohols 1̲4̲6̲ and 1̲4̲7̲ and for one reaction of the corresponding acetates. The conformational effects were found to be much smaller than those observed in 6-merabered rings. Explanations of this difference are given. The preparation of the ⍺, β-unsaturated lactones 1̲6̲3̲ and 1̲6̲4̲, the β-methyl-⍺, β-unsaturated lactones 1̲8̲5̲ and 1̲8̲̲6̲̲, the dimethyl lactones 1̲5̲4̲ and 1̲5̲5̲ and the epoxides 1̲9̲7̲ and 1̲9̲8̲ are described. The resulting geometry of double bonds and the stereochemistry of substituents are explained in terms of conformational preferences. [Formula Omitted] / Science, Faculty of / Chemistry, Department of / Graduate

Macrocyclic polyether sulfides have been prepared by reacting an oligoethylene glycol dichloride with a dithiol in refluxing basic ethanol. The following new compounds were prepared: 1,5-dithia-(19- crown-6), 3-hydroxy-1,5-dithia-(19-crown-6), 1,4-dithia-(21-crown-7), 3-hydroxy-1,5-dithia-(22-crown-7), and 1,4-dithia-(24-crown-8). One other previously reported macrocyclic polyether sulfide was also prepared. The thesis includes a review of macrocyclic sulfides and other related compounds, the thermodynamics of interaction of several macrocyclic polyether sulfides with Ag^+, Hg^2+, and Pb^2+ ions, and a discussion of the structure of these materials.