Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Part One. The synthesis of polycyclic compounds usually requires various synthetic approaches to construct the required carbon skeletons. This thesis describes a sequence which leads to the preparation of the tricylo (6.3.0.{dollar}0\sp{lcub}2,6{rcub}{dollar}) undecane skeleton found in a number of physiological fungal metabolites. The key steps in this sequence are photochemical cycloaddition of the enol of 5,5-dimethylcyclohexane-1,3-dione to a cyclopentene, followed by intramolecular reductive coupling of the dione with a low valence titanium compound. A formal synthesis of the fungal metabolite hirsutene is described using this procedure. The route involves the photochemical (2+2) cycloaddition of 5,5-dimethylcyclohexane-1,3-dione to 2-methyl-2-cyclopentenol, followed by the treatment of the silylated photoadducts with a low valence titanium reagent resulting in intramolecular reductive coupling to give the hirsutene carbon skeleton with the desired regiochemistry. Desilylation with fluoride ion, followed by sequential catalytic hydrogenation and Jones' oxidation completed the formal synthesis by yielding the norketone, obtained by ozonolysis of hirsutene.;Part Two. This part of the thesis describes the studies performed to determine the nature, and the reactive species in the photoannelation reaction of N-benzoylindole with cyclopentene which was found to proceed via a triplet state. The existence of a solvent polarity dependent charge-transfer triplet excited state, in addition to a solvent polarity independent triplet state, was proposed to rationalize the rate constant values obtained for N-benzoylindole from a combination of dilution, quenching and triplet counting experiments.;The fluorescence properties of various N-carbonyl substituted indoles 142a and 156 - 162 were examined. The N-benzoylindole derivatives 142a and 158 - 160 were shown to fluoresce weakly at anomalously long wavelengths and were dependent on the polarity of the solvent used. It was concluded that the initially formed singlet excited state is non-emissive and can relax to an intramolecular charge-transfer state which is weakly fluorescent. The solvent induced shifts in the wavelength of the fluorescence emission correlate well with Lippert equation. A poor correlation with the empirical {dollar}{lcub}\rm E\sb{lcub}T{rcub}{rcub}(30){dollar} solvent polarity parameter was observed.



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