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

 

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dc.contributor.advisor Jackson, Graham Ellis en_ZA
dc.contributor.author Nair, Margie May en_ZA
dc.date.accessioned 2015-12-28T06:11:09Z
dc.date.available 2015-12-28T06:11:09Z
dc.date.issued 1994 en_ZA
dc.identifier.citation Nair, M. 1994. The application of nuclear magnetic resonance in the structural elucidation of natural products. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/16004
dc.description Includes bibliographical references. en_ZA
dc.description.abstract 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. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Chemistry en_ZA
dc.title The application of nuclear magnetic resonance in the structural elucidation of natural products en_ZA
dc.type Master Thesis
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Science en_ZA
dc.publisher.department Department of Chemistry en_ZA
dc.type.qualificationlevel Masters
dc.type.qualificationname MSc en_ZA
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation Nair, 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/11427/16004 en_ZA
dc.identifier.chicagocitation Nair, 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/11427/16004 en_ZA
dc.identifier.vancouvercitation Nair 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/11427/16004 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


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