The oleanane and ursane triterpenoids

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

Abstract

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
• URI: https://theses.gla.ac.uk/id/eprint/72512