Thesis (Ph. D.)--University of Washington, 1985. / Vita. Bibliography: leaves [34]-35.

Thesis (Ph.D.)--Boston University. / Earlier work has shown that alumina at 350° acts on tetrahydrofurfuryl alcohol labeled at its external methylene group with carbon-14, as well as on dihydropyran ([delta^2]-dihydropyran) labeled at its 6 position with carbon-14 to produce an equimolecular mixture of dihydropyran2-C14 and dihydropyran-6-C14. The present work inquires into the possibility of oxygen and of hydrogen exchange in dihydropyran in contact with alumina under the same conditions. Dihydropyran-O18 was synthesized for use in oxygen exchange experiments. Tetrahydrofurfuryl chloride, prepared from the correspondingalcohol with thionyl chloride and pyridine, was treated with sodium to give 4-penten-1-ol. This alcohol was converted to 1-bromo-4-pentene with phosphorus tribromide in pyridine. Reaction of the Grignard derivative of the bromo compound with formaldehyde-O18 gave 5-hexen-1-o1-O18s · The labeled formaldehyde was obtained by pyrolyzing labeled paraformaldehyde, which in turn was prepared from ordinary paraformaldehyde by depolymerization to formaldehyde, exchange of oxygen with water-O18, and repolymerization. A mixture of 5-hexen-1-o1-O18 and 5-hexen-1-ol-1-C14 was ozonized and the product dehydrated to give dihydropyran labeled with oxygen-18 and (at position 6) with carbon-14 [TRUNCATED]

This investigation has been geared towards several aspects of chromone chemistry. Selected 2-(N,N-dimethylarnino)chromones have been synthesized via 2-hydroxyacetophenone boron difluoride complex intermediates, and potentiometric analysis of these compounds in ethanolwater has been used to determine the influence of substituents on their basicity. The pKa values have been found to lie within a narrow range (1.92 - 2.52), and the observed substituent effects have been rationalized with the aid of semi-empirical and ab initio molecular orbital calculations. An efficient route has been developed for the synthesis of the naturally-occurring chromone, "granulosin" [7,8-(methylenedioxy)-2-propylchromone], and several C-2 side chain analogues in good yields, by condensing 2'-hydroxy-3',4'-(methylenedioxy)acetophenone with a range of ethyl carboxylate esters. These compounds show significant cytotoxic activity against the brine shrimp, Artemia salina, and two of them, the 2-ethyl and 2-benzyl derivatives also show 100% activity as pesticides on Beet army worms (BAW). Another naturally-occurring chromone derivative, 5-hydroxy-2-isopropyl-7-methoxychromone, and four C-2 side chain analogues have been prepared in moderate yields. These compounds also show significant cytotoxic activity against the brine shrimp, Artemia salina, and it is apparent that the presence of the hydroxyl group at C-5 is critical for such activity. The electronimpact mass spectra of both series of chromone derivatives have been investigated, permitting the elucidation of characteristic fragmentation patterns. In work directed towards the synthesis of potential HIV -1 protease inhibitors, five novel chromone-containing analogues of the clinically useful drug, ritonavir, have been synthesized. The design strategy has involved the coupling of substituted chromone-2- carboxylic acids with a specially prepared, hydroxyethylene dipeptide isostere to afford ritonavir analogues containing chromone termini. An interactive docking procedure has been used to explore the docking of ritonavir and the novel chromone-containing analogues into ' the active site of the enzyme, and has indicated the capacity of the ritonavir analogues to form hydrogen-bonds with the HJV-l enzyme receptor. Various substituted cbromone-3-carbaldehydes, which have been synthesized from the corresponding o-hyclroxyacetophenones using Vilsmeier-Haack methodology, have been examined as substrates for Morita-Baylis-Hillman reactions, using 3-hyclroxyquinuclidine as the catalyst and arcylonitrile and methyl acrylate as the activated alkenes. Optimization of the reaction conditions has permitted efficient conversion of the cbromone-3-carbaldehydes to the Morita-Baylis-Hillman products and, in some cases, dimeric products, within 24 h. Heating of the Morita-Baylis-Hillman products, arising from reactions with methyl acrylate, at 80 ºC for 3 h in the presence of DABCO as catalyst, has been shown to effect transformation to the corresponding dimers in good yield.

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Thesis (MSc. (Chemistry)) -- University of Limpopo, 2015 / Alkyne-quinoxaline compounds were successfully synthesised form the cross-coupling of 2-benzenesulfonyloxyquinoxaline with terminal alkynes. The current study demonstrates the ability of benzenesulfonyloxy as a good leaving group in Sonogashira coupling reaction, generating a number of alkyne-quinoxaline compounds. The structures of the synthesised compounds were characterised through the comprehensive analysis of spectroscopic data from NMR, HPLC-MS and others selected compounds with IR. Several alkyne-quinoxaline compounds were synthesised in moderate to good yields. During analysis, it was observed that the highest yield was obtained when using 4-(trifluoromethyl)phenylacetylene 4e and the lower yield was obtained when using the 3-ethynylthiophene 4s as a substrate. The alkyne-quinoxaline compounds were investigated for 1,3-dipolar cycloaddition which was done from 2-ethylquinoxaline 6. The 1,3-dipolar cycloaddition reactions were successful and the compounds were obtained in good yields. The in vitro analysis on anti-tubercular screening against H37RvMA strains of M tb reveals that compounds 5e and 5o which contained a trifluoroanisole moiety showed promising activity amongst all the synthesised compounds. The compounds were having MIC90 values 11.8 μM and 12.7 μM respectively, however, they were found to be less active than rifampicin. Compounds 5a, 5b, 5e, 5g, 5h, 5i, 5I, and 5r were evaluated for anti-cancer activity on A549 cells. The results have showed that 5i was able to retard the migration of A549 cells in the Wound-Healing Migration Assay. / National Research Foundation (NRF) Sasol Inzalo Foundation

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

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