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|Title: ||The synthesis and structural examination of 3alpha, 5-cyclo-5alpha-androstane steroids.|
|Authors: ||Gibb, Bruce Clark|
|Supervisors: ||Cox, P. J.|
MacManus, S. M.
Turner, A. B.
|Issue Date: ||Mar-1992|
|Publisher: ||The Robert Gordon University|
|Citation: ||COX, P. J., MACMANUS, S. M., GIBB, B. C., NOWELL, I. W. and HOWIE, R. A., 1990. Structure of 3beta-hydroxy-5-androsten-17-one (DHEA) monohydrate. Acta Crystallographica C, C46(2) pp. 334-336|
GIBB, B. C., 1990. Crystal and molecular structure of 6beta-hydroxy-3alpha,5-cyclo-5alpha-androstan-17-one. Journal of Crystallographic and Spectroscopic Research, 20 (5), pp. 415
|Abstract: ||The work described in this thesis is based on the
synthesis and structural examination of several cyclosteroids.
The a-aromatic steroid 3a, 5-cyclo-5c-androstan-6beta-ol-
17-one was used as a lead compound in an attempt to produce,
in particular, the 17a-ethynyl derivative, the 6beta-methyl
derivative and the 7a-hydroxy, 6beta-methyl derivative. Full
experimental details of the various routes are provided. Xray
crystallography, along with standard spectroscopic
techniques, were utilised in structural determinations. To
complement these techniques molecular mechanics were also
utilised to predict spectroscopic results and to structurally
define the products.
The biological significance of steroids with respect to
contraception is outlined and the chemistry of the cyclopropane
ring discussed. A critical evaluation of the synthesis
of cyclopropane steroids and the alkylation of steroids has
been made. The objectives and methodologies behind recent
innovations are discussed.
An improved synthesis of the lead compound, from dehydroepiandrosterone,
was achieved. The chemical and spectral
implications of the introduction of a-aromaticity into the
steroid nucleus is discussed.
The synthesis of the ethynyl derivative, was achieved
in increasing yields by four different routes.
Synthesis of the 6beta-methyl derivative was considered
via four different pathways. Three of these routes gave the
important 6-methylene precursor but insufficient quantities
prevented the formation of the desired molecule.
Formation of the 7a-hydroxy, 6beta-methyl derivative, as
well as its 6beta-hydroxy, 7a-methyl isomer has been accomplished.
However, instability of the epoxide precursor
resulted in low yields.
Two novel single crystal X-ray structures have been
elucidated and X-ray powder diffraction data obtained on a
third. Results of the two determinations have been published.
The accurate geometrical details of these compounds
formed a basis for subsequent molecular mechanics calculations.
Molecular modelling was used to aid product identification,
determine theoretical product stability, i. e., potential
reaction outcome and to support spectroscopic data.|
|Appears in Collections:||Theses (Pharmacy & Life Sciences)|
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