The oleanane and ursane triterpenoids

Allan, George Graham (1956) The oleanane and ursane triterpenoids. PhD thesis, University of Glasgow.

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The work described in this thesis is conveniently considered in three independent sections. Section (l). The constitution of iso-beta-amyradienonyl acetate has been critically examined by reductive methods and confirmed, and it is now systematically named 12-oxotaraxera-9 (11):14-dien-3beta-yl acetate as a result of its relationship to the naturally occurring taraxerol. Mechanisms for the conversion of several taraxerane derivatives to oleanane derivatives are proposed. Catalytic hydrogenation of iso-beta-amyradienonyl acetate proceeds via a new trienyl acetate, neo-beta-amyratricnyl acetate, to yield an isomer of beta-amyrin acetate, neo-beta-amyrin acetate. These compounds belong to a series which have a new type of triterpenoid carbon skeleton formed as a result of multi-methyl group migration. Possible structures for compounds in this series and reaction mechanisms for their formation are discussed. Section (2). A general investigation of the chemistry of 18a-oleanane derivatives and a comparison with the oleanane and ursane analogues under the subsections. (A). Oxidation of 11-oxo-12-en-3beta-yl acetates. (B). Dehydrations of 11beta-hydroxy-12-en-3beta-yl acetates. (C). Oxidation of 12-en-3beta-yl acetates. (D). Bromination of 12-oxo-an-3beta-yl acetates. (E). Acid rearrangements of -9 (11):12-dien-3beta-yl acetates. (F). Ultra-violet absorption spectra. (G). Reactions of 12-oxo-9(ll)-en-3beta-yl acetates. shows that rings D and E in alpha-amyrin are cis-beta-fused. Section (3). The structures of the well known dehydration products of alpha-amyrin and related alcohols, d-a-amyradiene, l-alpha-amyradiene, a=arayradienone-III, d-alpha-amyratriene, dichloro-alpha-amyradiene, and 1-alpha-amyratrien, have been examined and elucidated. Reduction of alpha-ainyradienone-I yields d-alpha-arayradiene which has been converted to l-alpha-amyradiene, also obtained from a-amyradienone-III. Reduction and dehydration of alpha-amyradienone-I gives d-alpha-amyratriene and demonstrates the constitution of dichloro-alpha-amyradlene, alpha-Amyradienone-III has been prepared stepwise from alpha-amyradienone-I via alpha-arayradienone-II, and has been converted to 1-alpha-amyretriene. Some analogous reactions in the oleanane series have been investigated.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: F S Spring
Keywords: Organic chemistry
Date of Award: 1956
Depositing User: Enlighten Team
Unique ID: glathesis:1956-72512
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 11 Jun 2019 11:06
Last Modified: 11 Jun 2019 11:06

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