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Title: Studies in triterpenoids and steroids
Author: Shaw, James I.
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1957
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An Examination of the steroidal sapogenin content of sisal juice resulted in the isolation of three known sapogenins, neotigogenin, neohecogonin (sisalagenin) and hecogenin, and a compound of unknown structure, compound S acetake. Compound S acetate on Wolff-Kishner reduction gave tigogenin acetate, indicating that compound S acetate is a ketotigogenin acetate. Unsuccessful attempts were made to determine the position of the carbonyl group. Bromo- and A-Chlorocholest-A-en-3-one An unambiguous method of preparation of 4-bromo-and 4-chloro-cholost-4-en-3-one has been found. This comprised in treatment of 4p:5-epoxycoprostan-3-one with hydrobromic or hydrochloric acid. The ultra-violet absorption characteristics of these compounds and derivatives were examined. q-Amyrln Experiments leading to a new stereoformula for alpha-amyrin are described including the conversion of a simple ursane derivative to an olearane derivative. With the nature of ring E still in doubt, experiments with the object of introducing- reactive groupings in ring E were carried out in order to obtain some direct evidence to the nature of this ring. A thorough examination of the oxidation of ursa-9(H)s 12-dien-3beta-yl acetate was made, four neutral compounds being isolated and identified. The first recorded preparation of an ursane derivative with a double bond in ring E is described. Four compounds with an 18-19 double bond were obtained, these are, ursa-9(11): 12:18-trien-3beta-yl acetate, 3beta:12-diacetoxyursa-9(11): 12:18-triene, 12-oxouraa-9(11):18-dien-3betayl acetate, and 12-oxours-18-dien-3beta-yl acetate. A discussion of the merits of the two principal stereoformulae for alpha-amyrin (i.e. the six-membered ring E, and the five-membered ring E) is given.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available