Isolation, Structural and Stereochemical Studies in the Terpenoid Field

Fulke, John W. B (1968) Isolation, Structural and Stereochemical Studies in the Terpenoid Field. PhD thesis, University of Glasgow.

Abstract

This thesis consists of three sections, each concerned with an aspect of terpenoid chemistry. The first is devoted to the stereochemistry of the diterpenoid lactone, marrubiin. The gross structure of this compound has been secure for some time, but the stereochemistry, apart from the A:B ring junction has been a matter of controversy. Two approaches to the problem were used: the more facile method was felt to be by X-ray analysis of a heavy atom derivative, but attempts to prepare a suitable derivative proved unsuccessful; the other approach was by spectroscopic studies of various derivatives of marrubiin. Combined with information obtained by previous workers, the interpretation of these studies permitted a firm assignation of the stereochemistry of marrubiin. The second section is concerned with the examination of extractives of the heartwood of Guarea Globra. The compounds isolated proved to be new triterpenoids. The first one described was shown to be a mixture of C28, C29 and C30 homologues, not readily separable by chromatographic methods, On the basis of chemical and spectroscopic evidence, tentative suggestions as to the structure of these compounds have been made. Eight other compounds were isolated, of which four were closely related, and tentative structures for them proposed, while for the other four compounds, only in the case of one, was deficient information obtained to allow a tentative assignment of structure. The X-ray Crystallographic analysis of the p-iodo-benzoate of triol Q acetonide is described in the final section. Triol Q is a diterpene triol from Brythroxylon Monogynum Roxb. , isolated as the acetate acetonide, which was converted to the p-iodobonzoate. The structure was solved by Patterson and Fourier syntheses using the heavy atom method of determining the phase angles in the Fourier summations. The atomic parameters were refined by the method of least squares to an R value of 14.4, and since the purpose of the analysis had been achieved, i. e. the determination of the stereochemistry of triol Q, the refinement was terminated. The molecular parameters and geometry are detailed in the tables and figures at the end of this section.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Organic chemistry
• Date of Award: 1968
• Depositing User: Enlighten Team
• Unique ID: glathesis:1968-78462
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 28 Feb 2020 12:09
• Last Modified: 28 Feb 2020 12:09
• URI: https://theses.gla.ac.uk/id/eprint/78462