The application of nuclear magnetic resonance in the structural elucidation of natural products

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dc.contributor.advisorJackson, Graham Ellisen_ZA
dc.contributor.authorNair, Margie Mayen_ZA
dc.date.accessioned2015-12-28T06:11:09Z
dc.date.available2015-12-28T06:11:09Z
dc.date.issued1994en_ZA
dc.descriptionIncludes bibliographical references.en_ZA
dc.description.abstractMultipulse Nuclear Magnetic Resonance (NMR) techniques were investigated via structural assignment of various natural products. The natural products chosen for investigation of 2D NMR spectroscopy as a structural tool were the opium alkaloids codeine and papaverine, the diterpenoid alkaloids delphinine and aconitine and the triterpenoid derivatives of cucurbitaceae. One dimensional NMR spectroscopy viz 1H, 13C and Distortionless Enhancement by Polarisation Transfer (DEPT) spectroscopy was initially applied to obtain a level of indication of the complexity of the structural problem solving. Various multipulse techniques were chosen depending on the sample quantity available, the sensitivity of the technique, the information provided and its applicabilty in the field of natural products. Both homonuclear scalar and dipolar correlation as well as short and long range heteronuclear correlation was investigated. The homonuclear Correlation Spectroscopy (COSY) experiment which revealed scalar 1H-1H scalar correlations was adequate for the structural assignment. The Heteronuclear Multiple Quantum Coherence (HMQC) experiment offered greater sensitivity on small sample quantities whilst the long range Heteronuclear Correlation (HETCOR) and Heteronuclear Multiple Bond Coherence (HMBC) experiments were essential for complete assignment of the quaternary groups. The stereochemical designation of some of the compounds was confirmed using the Rotating Frame Overhauser Enhancement Spectroscopy (ROESY) experiment which proved to be a more applicable pulse sequence for the natural products under investigation. The 1H and 13C assignments of these derivatives and the experimental approach used to obtain this data was compared to that present in the literature. The results indicate that apart from offering tremendous versatility depending on the special attributes of the compound, two dimensional NMR techniques are imperative for the unambiguous structural assignment of natural products.en_ZA
dc.identifier.apacitationNair, M. M. (1994). <i>The application of nuclear magnetic resonance in the structural elucidation of natural products</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Chemistry. Retrieved from http://hdl.handle.net/11427/16004en_ZA
dc.identifier.chicagocitationNair, Margie May. <i>"The application of nuclear magnetic resonance in the structural elucidation of natural products."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Chemistry, 1994. http://hdl.handle.net/11427/16004en_ZA
dc.identifier.citationNair, M. 1994. The application of nuclear magnetic resonance in the structural elucidation of natural products. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Nair, Margie May AB - Multipulse Nuclear Magnetic Resonance (NMR) techniques were investigated via structural assignment of various natural products. The natural products chosen for investigation of 2D NMR spectroscopy as a structural tool were the opium alkaloids codeine and papaverine, the diterpenoid alkaloids delphinine and aconitine and the triterpenoid derivatives of cucurbitaceae. One dimensional NMR spectroscopy viz 1H, 13C and Distortionless Enhancement by Polarisation Transfer (DEPT) spectroscopy was initially applied to obtain a level of indication of the complexity of the structural problem solving. Various multipulse techniques were chosen depending on the sample quantity available, the sensitivity of the technique, the information provided and its applicabilty in the field of natural products. Both homonuclear scalar and dipolar correlation as well as short and long range heteronuclear correlation was investigated. The homonuclear Correlation Spectroscopy (COSY) experiment which revealed scalar 1H-1H scalar correlations was adequate for the structural assignment. The Heteronuclear Multiple Quantum Coherence (HMQC) experiment offered greater sensitivity on small sample quantities whilst the long range Heteronuclear Correlation (HETCOR) and Heteronuclear Multiple Bond Coherence (HMBC) experiments were essential for complete assignment of the quaternary groups. The stereochemical designation of some of the compounds was confirmed using the Rotating Frame Overhauser Enhancement Spectroscopy (ROESY) experiment which proved to be a more applicable pulse sequence for the natural products under investigation. The 1H and 13C assignments of these derivatives and the experimental approach used to obtain this data was compared to that present in the literature. The results indicate that apart from offering tremendous versatility depending on the special attributes of the compound, two dimensional NMR techniques are imperative for the unambiguous structural assignment of natural products. DA - 1994 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1994 T1 - The application of nuclear magnetic resonance in the structural elucidation of natural products TI - The application of nuclear magnetic resonance in the structural elucidation of natural products UR - http://hdl.handle.net/11427/16004 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/16004
dc.identifier.vancouvercitationNair MM. The application of nuclear magnetic resonance in the structural elucidation of natural products. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Chemistry, 1994 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/16004en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Chemistryen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherChemistryen_ZA
dc.titleThe application of nuclear magnetic resonance in the structural elucidation of natural productsen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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