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Stereoselective reactions of 16-Methylene 19-Norsteroids
The influence of the 17-substituent upon epoxidation of 3-methoxy-16-methylene-estra- 1,3,5(10)-trien-17-one and the derived 17β-hydroxy and 17β-acetoxy compounds was investigated. Alkaline hydrogen peroxide epoxidation of 3-methoxy-16-methyleneestra- 1,3,5(10)-trien-17-one occurred in good yields,...
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| Format: | Thesis |
| Language: | English |
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Department of Chemistry
2016
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| _version_ | 1867611350191046656 |
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| access_status_str | Open Access |
| author | Kaiser, Delene Anne |
| author2 | Bull, James R |
| author_browse | Bull, James R Kaiser, Delene Anne |
| author_facet | Bull, James R Kaiser, Delene Anne |
| author_sort | Kaiser, Delene Anne |
| collection | Thesis |
| description | The influence of the 17-substituent upon epoxidation of 3-methoxy-16-methylene-estra- 1,3,5(10)-trien-17-one and the derived 17β-hydroxy and 17β-acetoxy compounds was investigated. Alkaline hydrogen peroxide epoxidation of 3-methoxy-16-methyleneestra- 1,3,5(10)-trien-17-one occurred in good yields, but poor stereoselectivity was obtained due to mechanistic considerations. Poor stereoselectivity was also obtained for the peracid epoxidation of 3-methoxy-16-methylene-estra-1,3,5(10)-trien-17β-ol, due to the pseudo-equatorial position of the 17β-hydroxyl group. However, excellent stereoselectivity was obtained using Sharpless conditions (vanadium catalyst), which gave only the epoxide syn to the hydroxyl group, in good yields. Surprisingly, peracid epoxidation of 3-methoxy-16-methylene-estra-1,3,5(10)-trien-17β-yl acetate favoured equatorial attack resulting in a 2:1 ratio of the (16R)- and (16S)-epoxide isomers, instead of the expected axial approach by the peracid. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/22136 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2016 |
| publishDateRange | 2016 |
| publishDateSort | 2016 |
| publisher | Department of Chemistry |
| publisherStr | Department of Chemistry |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/22136 Stereoselective reactions of 16-Methylene 19-Norsteroids Kaiser, Delene Anne Bull, James R Chemistry The influence of the 17-substituent upon epoxidation of 3-methoxy-16-methylene-estra- 1,3,5(10)-trien-17-one and the derived 17β-hydroxy and 17β-acetoxy compounds was investigated. Alkaline hydrogen peroxide epoxidation of 3-methoxy-16-methyleneestra- 1,3,5(10)-trien-17-one occurred in good yields, but poor stereoselectivity was obtained due to mechanistic considerations. Poor stereoselectivity was also obtained for the peracid epoxidation of 3-methoxy-16-methylene-estra-1,3,5(10)-trien-17β-ol, due to the pseudo-equatorial position of the 17β-hydroxyl group. However, excellent stereoselectivity was obtained using Sharpless conditions (vanadium catalyst), which gave only the epoxide syn to the hydroxyl group, in good yields. Surprisingly, peracid epoxidation of 3-methoxy-16-methylene-estra-1,3,5(10)-trien-17β-yl acetate favoured equatorial attack resulting in a 2:1 ratio of the (16R)- and (16S)-epoxide isomers, instead of the expected axial approach by the peracid. 2016-10-14T06:27:22Z 2016-10-14T06:27:22Z 1991 Master Thesis Masters MSc http://hdl.handle.net/11427/22136 eng application/pdf Department of Chemistry Faculty of Science University of Cape Town |
| spellingShingle | Chemistry Kaiser, Delene Anne Stereoselective reactions of 16-Methylene 19-Norsteroids |
| thesis_degree_str | Master's |
| title | Stereoselective reactions of 16-Methylene 19-Norsteroids |
| title_full | Stereoselective reactions of 16-Methylene 19-Norsteroids |
| title_fullStr | Stereoselective reactions of 16-Methylene 19-Norsteroids |
| title_full_unstemmed | Stereoselective reactions of 16-Methylene 19-Norsteroids |
| title_short | Stereoselective reactions of 16-Methylene 19-Norsteroids |
| title_sort | stereoselective reactions of 16 methylene 19 norsteroids |
| topic | Chemistry |
| url | http://hdl.handle.net/11427/22136 |
| work_keys_str_mv | AT kaiserdeleneanne stereoselectivereactionsof16methylene19norsteroids |