Part I. Diels-Alder cycloadditions of 1,2,3,4,9,9-hexachloro-1α,4α,4aα,8aβ-tetrahydro-l,4-methanonaphthalene (32) and 1,2,3,4,9,9-hexachloro-lα,4α,6,7- tetrahydro-l,4-methanonaphthalene (33) to 4-methyl- and 4-phenyl-l,2,4-triazoline-3,5-dione [MTAD and PTAD, respectively] and to N-methylmaleimide (NMM) have been studied. The structures of several of the resulting cycloadducts were determined by X-ray crystallographic methods. The observed stereoselectivity of each of these Diels-Alder reactions was further investigated via application of theoretical methods. Thus, semiempirical (AMI) and ab initio molecular orbital calculations were used to calculate relative energies. Ab initio calculations were employed to perform frontier molecular orbital analyses of diene-dienophile interactions.

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It is the purpose of this work to prepare a series of these chalcones containing the thiophene ring. The compounds were prepared by the condensation of a series of benzaldehydes with acetylthiophene dissolved in dry ethylacetate and saturated with dry HCl. The benzaldehyde compounds were benzaldehyde, m-hydroxybenzaldehyde, o-hydroxybenzaldehyde, O-p-dihydroxybenzaldehyde and vanillin. To prevent the oxidation of the hydroxy groups of the benzaldehydes, the compounds were benzolated with benzoylchloride. The condensed products were debenzoylated with NaOH solution in an atmosphere of nitrogen to prevent oxidation during the debenzoylation process.

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<p> Experimental carbon-13 nuclear magnetic resonance chemical shifts are given for substituted 1,3-dioxanes, tetrahydrofurans, dihydro-2-furanones and succinic anhydrides. The experimental data are used to improve and extend the carbon-13 chemical shift prediction parameters which allow one to estimate with considerable accuracy unknown chemical shift values.</p> / Thesis / Master of Science (MSc)

When subjected to ultraviolet radiation in the presence of an alkene, s-triazolo[4,3-b]pyridazine (STP) undergoes an unusual 3 + 2 photocycloaddition wherein the alkene adds to the 1 and 8 positions of STP with concommitant N4-N5 bond cleavage yielding 5,6-disubstituted-6,7-dihydro-7-methylene (and 7-cyanomethyl)-5H-pyrrolo[1,2-b]-s-triazoles. Amides and esters of indole-3-carboxylic acid have been synthesized by a novel reaction employing the ultraviolet irradiation of 3-diazo-4-oxo-3,4-dihydroquinoline (QDA) in the presence of amines or alcohols respectively. QDA, when irradiated, is postulated to undergo an internal Wolff Rearrangement to Indole-3-ketene which can add any amine or alcohol to form the corresponding amide or ester in modest to good yield.

SERS (surface-enhanced Raman spectroscopy) has the potential to be used in a variety of commercial and basic applications, which often rely on molecules that are bound to a nanostructured metal surface. Thiols are usually used as the intermediate to modify the substrate surface for SERS. In recent years, N-heterocyclic carbene (NHC) has been introduced as an alternative approach for metal surface modification. Nanostructured gold surfaces suitable for SERS had been modified by NHC species. Those studies showed the promising of the NHC modification route for the fabrication of a robust platform for SERS. The objective of this work is to explore the SERS characteristics of NHC species on silver surfaces. The interactions between two different NHC molecules and a nanostructured silver surface, instead of a gold surface, were studied for the first time. The experiments were realized in electrochemical conditions, using a three-electrodes system, to fully test the stability of the NHC-modified surfaces. The SERS spectra were compared to theoretical calculations and normal Raman in order to identify the vibrational characteristics of the NHC molecules. The effects of different NHC molecule substituents on the electrochemical stability of the surface were also discussed. The results showed that NHC molecules can be decomposed on the silver surface easily under electrochemical conditions. This contrast with the observations in gold, where the NHC monolayers showed a high level of stability. This work also discusses potential side products which may be derived from the decomposition of the NHC molecules. Raman spectra of potential side products were collected and compared to the NHC SERS collected under electrochemical control at different potentials. This study provides insights into the influence of the substituents at the NHC on their stability under the electrochemical condition, which should guide the development of future applications. / Graduate

Ph. D.