Thesis (M.S.)--Oregon State University, 1987. / Typescript (photocopy). Includes bibliographical references (leaves 65-71). Also available online.

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The photochemistry of a variety of tetrahydro-1,4-naphthoquinones (structure 1) has been investigated. These were synthesized by Diels-Alder reaction of corresponding p-quinones and acyclic-1,3-dienes [diagram omitted]. Three substituent-dependent types of reactions were observed: (1) for adducts possessing hydrogen substituents at C₄a and C₈a (bridgehead position), the prevalent process was one of abstraction of a β-hydrogen atom from C₅(or equivalently, C₈) by excited carbonyl oxygen. In general, three product types were then observed, derived from carbon-carbon bond formation (proceeded in two instances by conformational rotation about the C₄a - C₈a bond) in the bisallylic radical so produced. Placing a methyl or phenyl substituent at C₂ renders the β-hydrogens non-equivalent, and abstraction occurs in accord with expectations based on the formation of the more stable biradical intermediate. In adducts possessing bridgehead substituents, rotation about the C₄a - C₈a bond in the biradical is suppressed and only a single product type (enone alcohol) is formed, which possesses the same relative conformation as the biradical and starting adduct. In the case where the bridgehead substituents are carboxymethyl, however, secondary photolysis in benzene solution occurs, giving rise to a product where the bridgehead substituents are nearly eclipsed. (2) For the adduct possessing exo-methyl substituents at positions 5 and 8 as well as methyls at the bridgehead positions and at and C₂ and C₃, hydrogen abstraction was partially suppressed in favor of a process tentatively concluded to involve Ύ~hydrogen abstraction by excited enone carbon, giving rise to a product, the formation of which again requires little conformational change in the biradical. (3) For adducts possessing endo-methyl substituents at C₅ and C₈ as well as bridgehead substituents, a novel oxetane product was observed, formally the result of a cycloaddition reaction involving the remote double bond and one of the carbonyl groups. The oxetane derived from the duroquinone adduct was found to be photolabile, giving back starting material and, eventually, a quantitative conversion to a novel cage diketone. The reactivity differences for these systems, as well as for those previously studied in our laboratory, are interpreted as being due to the effects of substituents on the energy barrier to conformational isomerization in the biradical intermediates. Finally, the potential utility of these photochemical reactions for the synthesis of unusual ring systems is noted. / Science, Faculty of / Chemistry, Department of / Graduate

The thesis is presented in five parts. In the first, our present knowledge of red alder {Alnus rubra Bong.) is summarized and shows a lack of specific knowledge about its seed and reproductive biology. The aims of the first study were (1) to determine the occurrence and (if present) the nature of seed dormancy; (2) to determine whether seed vigour was related to geographic location of different provenances; and (3) to examine the influence of stratification and presoaking on seed germination. Germination tests were carried out on stratified, presoaked and untreated seeds collected from several locations throughout the species' range. With one exception (seed from Haney, B. C. collected in 1976), dormancy was not a significant factor in preventing germination of untreated seeds. Germination of these exceptional seeds was improved by cold stratification for eight days and to a lesser extent, by presoaking in tap water for 2h hours. Seed collected from the same area before and after these tests showed no dormancy. Germination percent was relatively high for treated and untreated seeds of other provenances and showed few differences between provenances. There were more pronounced differences in seed vigour, as measured by germination value, between provenances. There appeared to be no direct relationship between the differences observed and geographic factors, as found in many wide ranging species native to western North America. The aims of the second study were (1) to examine the effects of fertilization and different soil types on root and nodule development, height growth, dry weight accumulation and root-shoot dry weight ratio of seedlings of red alder from different locations in its natural distribution; and (2) to relate observed differences between provenances to their geographic location. Early seedling development in fertilized and unfertilized seedlings front several sources and grown in different combinations of sand and a loamy soil, was examined. Root development was influenced by the type of growth medium and the nutrient status of the same. Nodulation, however, was little affected by these factors. Nodule development was more extensive on upper root branches than on lower ones. Fertilization increased height and dry weight, and lowered root-shoot dry weight ratio of seedlings. Height growth and dry weight accumulation were greater, and root-shoot ratio was lower in loam and in a loam-sand mixture (1:1 w/w) than in sand. Height growth did not differ between provenances. There were differences in dry weight and root-shoot ratio between provenances but these differences were not correlated with any geographic factor. In the last study, an attempt was made to identify endogenous gibberellins extracted from quiescent vegetative, male and female buds of red alder. Following fractionation of the extracts by silica gel partition chromatography, positive growth responses were obtained in the dwarf rice bioassay of several of the fractions. In gas-liquid chromatography, various fractions produced peaks with retention times similar to those of standard gibberellins. Although some qualitative indications were noted, it was not possible to confirm the presence and identity of gibberellins using combined gas-1iquid chromatography-mass spectrometry. Inadequate purification of extracts and low concentrations of endogenous gibberellins in the extracts were thought to be mainly responsible for this failure. The impact and implications arising from the results of these studies and -possible future directions for research are discussed in the final chapter. / Forestry, Faculty of / Graduate

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Thermally induced retro-Diels Alder (rDA) reaction has been extensively used for the preparation of many reactive intermediates in organic synthesis. But the uses of photo-retro Diels-Alder (PrDA) reaction in organic synthesis were sparingly reported in literature. Due to its spatial and temporal control, PrDA can be used in making of photosensitive materials, in drug delivery and also for mechanistic studies. Diels-Alder adducts of tetracyanoethylene (TCNE) and polyaromatic compounds (anthracene, napthacene, pentacene and phencyclone) were synthesized and were subjected to PrDA reaction through 254-nm irradiation. The quantum yield and the consequent photoreactivity of these DA adducts follow the following order. TCNE/naphthacene greater than] TCNE/anthracene greater than or equal to] TCNE/pentacene This trend was explained by a mechanism of charge-separated intermediates. The stability of the charge-separated intermediate is the governing factor of this trend of photoractivity of DA adducts. Based on these results it is possible to design a proper DA adduct and consequently predict the feasibility of the PrDA reaction.

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