Studies in Natural Product Chemistry

Gunn, Donald M (1967) Studies in Natural Product Chemistry. PhD thesis, University of Glasgow.

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This thesis entitled "Studies in Natural Product Chemistry" can be divided into three distinct sections. Section 1 deals with the structural elucidation of two glycosides, isolated iron the acetylated Ononis spinosa L. root extract. These compounds wore identifien as one tetraacetates of inermin 7-beta-D-glucoside (1) and homoinermin 7-beta-D-glucoside, on the basis of spectroscopic evidence and by enzymatic hydrolysis of their corresponding free glucosides. The discussion of these glucoside acetates is prefaced by a brief review of the naturally occurring pterocarpans, and a discussion of their probable biogenesis. Section 11 is concerned with the structural elucidation of the diterpenoids, erythroxytriol P (3) and erythroxytriol Q acetate (4), which occur in the heartwood of Erythroxylon monogynum Roxb. Their structures are suggested on the basis of spectroscopic and chemical evidence. During this study, ozonolysis of diol X acetonide (5) was shown to lead to the formation of an alpha-cyclopropyl ketone and unexpectedly to an alpha-ketol. The discussion is preceded by a review of relevant diterpene biogenesis. The third section commences with a review of epoxide isomerisation, with special reference to acid-induced ( baron trifluoride) and base-induced isomerisations. The subsequent discussion describes the acid-induced isomerisations of erythroxydiol acetonides X and Y (5 and 6), and preparation and characterisation of the epoxides from the derived olefins. The final part of this section deals with the effect of boron trifluoride and alkaline grade 1 alumina on these and other epoxides. Under acid catalysis, diterpenoid epoxides with and without the supposedly ideal sterical requirements for concerted "backbone" rearrangement were compared, with a view to elucidating further the factors involved in such rearrangements. These results were contrasted with those obtained from alkaline alumina treatment. The acid-base catalytic action of alumina did not effect "backbone" rearrangement in the steroidal system, but where beta-elimination was inhibited carbene insertion products could be obtained. The alpha-epoxide (7) derived from erythroxydiol Y acetonide showed an unusual J coupling involving an epoxide proton. The other interacting proton involved was shown to be the axial C-3 proton by deuteration experiments on the nor-ketone (8) followed by reaction of these deuterated ketones with the Corey methylide reagent to afford specifically deuterated alpha-epoxides.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Organic chemistry
Date of Award: 1967
Depositing User: Enlighten Team
Unique ID: glathesis:1967-78442
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 28 Feb 2020 12:09
Last Modified: 28 Feb 2020 12:09

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