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UBC Theses and Dissertations

Use of camphor in terpenoid syntheses Lamb, Nancy Ching-Yun


Camphor has been functionalised at the C(5), C(6), C(8) and C(9) positions by procedures previously developed and the corresponding derivatives have subsequently been utilised as key intermediates in mono- and sesquiterpenoid syntheses. The monoterpenoid analogues of the plant growth-promotor (-)-cis-sativenediol and the growth-inhibitor (-)-helminthosporal, (-)-5-exo, 6-exo-dihydroxycamphene and (+)-1,4-diformyl-2,3,3-trimethylcyclopentene respectively, have been prepared from (-)-camphor by a synthetic route involving the 'remote oxidation' of (+)-isobornyl acetate to a mixture of 5- and 6-oxoisobornyl acetates. The trans-diol (-)-5-endo, 6-exo-dihydroxycamphene was also obtained during this study. The synthetic monoterpenoids and their enantiomers were found to be devoid of growth-promoting or growth-inhibiting properties on two varieties of rice (Oryza sativa). The 'remote oxidation' technique has also been applied to the synthesis of nojigiku alcohol [(+)-6-exo-hydroxycamphene], a metabolite of Chrysanthemum japonense, from (+)-camphor. The structure, absolute configuration, and physical constants of this monoterpenoid alcohol and its derivatives have thus been established. (+)-9-Bromocamphor was used as a starting material for two unsuccessful synthetic approaches to the trisnorsesquiterpenoid albene, a metabolite of plants of the genera Petasites albus (L.) Gearth and Adenostyles alliariae (G.) Kern. One of these routes was based on the proposal that epi-β- santalene, a natural sesquiterpenoid which had previously been synthesised in our laboratory, could be a biosynthetic precursor of albene. However, during these investigations the original structure of albene was revised and a third synthetic route to this compound using (+)-8-bromocamphor as starting material was therefore studied. (+)-8-Bromocamphor has also been utilised as the starting material in a synthetic approach to clausantalene, a sesquiterpenoid isolated from Clausena indica 0liv. (Rutaceae). A synthesis of dehydroclausantalene and epidehydroclausantalene T_9-hydroxy-9-(3' -methyl-V -butenyl )camphenes] has been accomplished but the regio- and stereoselective hydration of these two compounds to clausantalene and its epimer respectively is still under investigation.

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