- Title
- An investigation of compounds occurring in leonotis species
- Creator
- Naidu, Krishna
- Subject
- Leonotis -- Analysis
- Subject
- Chemistry -- Analytic
- Subject
- Nuclear magnetic resonance
- Date Issued
- 1970
- Date
- 1970
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- vital:3852
- Identifier
- http://hdl.handle.net/10962/d1012934
- Description
- Two labdane diterpenoids 8-hydroxymarrubiin and leonitin were isolated from Leonotis dysophylla (Benth.) and Leonotis leonitis respectively. Spectral studies of 8-hydroxymarrubiin, C₂₀H₂₈ O₅ʻ showed the presence of a β -substituted furan, a Ϫ-lactone, three tertiary methyl groups and tertiary hydroxyl group (s). The NMR spectrum of 8-hydroxymarrubiin and marrubiin C₂₀H₂₈O₄ʻ were almost identical with the exception of the C₁₇- methyl group which appeared as a singlet in 8-hydroxymarrubiin and as a doublet in marrubiin. The extra oxygen atom was therefore assumed to be present as a hydroxyl group substituted in the C₈₋ position. This was further confirmed by the formation of an epoxide and a Ϫό-dilactone. Leonitin, C₂₀H₂₈O₇ʻ was shown by spectral and chemical evidence to be a diterpenoid dilactone possessing an ester function and an ether linkage. Comparison of the NMR spectra of compound X and leonitin suggested that the acetoxy function occurs in the C₂₀- position. This was further supported by the formation of a 'Ϫό -dilactone. The absence of a β -furan moiety was apparent from chemical and spectral evidence, A structure for leonitin is proposed and aspects of its stereochemistry discussed.
- Format
- 113 p.
- Format
- Publisher
- Rhodes University
- Publisher
- Faculty of Science, Pharmacy
- Language
- English
- Rights
- Naidu, Krishna
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