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Structural and synthetic studies of some pyrrolidine, tropane and bisbenzylisoquinoline alkaloids

posted on 2023-05-26, 21:45 authored by Leow, Huck Meng
A detailed phytochemical examination of the alkaloid content of four species of the family Proteaceae - Bellendena montana, Darlingia darlingiana, Darlingia ferruginea and Agastachys odorata - has been undertaken. A new group of pyrrolidine bases with a side-chain of varying length terminating in a phenyl group has been isolated from D. darlingiana. Spectroscopic and chemical evidence for the structures of five new C17 and three new C15 pyrrolidine bases are presented. The structural assignments were confirmed by syntheses, and in one case, by X-ray crystallography, which also established the absolute stereochemistry. Four new minor alkaloids of the pyranotropane-type have been isolated, three from B. montana and one from D. darlingiana. Four previously described pyranotropane alkaloids were reisolated from the Bellendena and Darlingia species; the presence of eight alkaloids of the tropane-type in the four species, including a unique tropene of biosynthetic interest in A. odorata, was also confirmed. Two of the tropane alkaloids have been synthesised and their absolute stereochemistries established. Progress towards the synthesis of a third tropane alkaloid is reported. Four unknown bases were also isolated from B. montana; evidence is presented to support a tentative trilactone structure proposed for one of these. Some general observations on the proteaceous alkaloids are made and a possible mode of biosynthesis of these alkaloids is suggested. Two species of the family Monimiaceae, Daphnandra johnsonii and Nemuaron vieillardii, were investigated. An examination of the alkaloid content of the rare new species, D. johnsonii, has supported its taxonomic classification as a distinct species. Three new bisbenzylisoquinoline alkaloids were isolated; one of these is unique amongst the biscoclaurine alkaloids of the head-to-head type in having a C6-hydroxyl group; the other two belong to the dibenzodioxin type of biscoclaurine alkaloids. Four known alkaloids which occur in other Daphnandra spp. were also isolated. A new bisbenzylisoquinoline alkaloid with a C5-C6' ether linkage has been isolated from N. vieillardii. Spectroscopic and chemical evidence for the structures of the new alkaloids are presented. The thesis is divided into three parts. The pyrrolidine alkaloids are discussed in Part I, the tropane alkaloids in Part II, and the bisbenzylisoquinoline alkaloids in Part III.


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Copyright 1979 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s). Thesis (Ph.D)--University of Tasmania, 1979. Includes bibliographical references

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