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The syntheses of some naturally derived naphthoquinones
Bibliography: pages 193-195.
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| Other Authors: | |
| Format: | Thesis |
| Language: | English |
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Department of Chemistry
2016
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| _version_ | 1867614141648207872 |
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| access_status_str | Open Access |
| author | De Koning, Charles Bernard |
| author2 | Giles, Robin G F |
| author_browse | De Koning, Charles Bernard Giles, Robin G F |
| author_facet | Giles, Robin G F De Koning, Charles Bernard |
| author_sort | De Koning, Charles Bernard |
| collection | Thesis |
| description | Bibliography: pages 193-195. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/22000 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:47:19.847Z |
| 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:11427/22000 The syntheses of some naturally derived naphthoquinones De Koning, Charles Bernard Giles, Robin G F Naphthoquinone Rifomycin Bibliography: pages 193-195. The synthesis of the naphthalene core of the ansamycin antibiotics, 8-acetyl-3-acetylamino-5,7-dihydroxy-1,4-naphthoquinone from benzoquinone by means of simple reactions including, Diels-Alder adduct formation, mild acetylation, oxime formation and Beckmann rearrangement in five steps with an overall yield of 22% is described in Chapter 1. The synthesis of the naturally occurring naphthoquinone derivative, possessing anti tumour and antiprotozoal properties, bikaverin is described in Chapter 2. Starting from vanillin the key intermediate 2-(2'-benzyloxy-6'-methyl-4'-methoxybenzoyl)-1,4,5,6,8-pentamethoxynaphthalene was prepared in six simple steps in an overall yield of 18%. This key intermediate was converted into bikaverin utilizing two independent routes. In the first route the benzyl group was removed from the key intermediate by hydrogenolysis followed by oxidative spiro ring formation , with 2,3-dichloro-5,6-dicyanobenzoquinone. After effecting xanthone ring formation and removal of two methyl groups with lithium iodide, bikaverin was produced in six steps in an overall yield of 32%. In the second route the key intermediate was first oxidised by silver (II) oxide this was followed by removal of the benzyl group and two methyl groups peri- to the quinone with boron trichloride, which led to spontaneous spiro ring formation, ultimately bikaverin was produced in three steps in an overall of 34%. The syntheses of the naturally occurring product ventiloquinone E and its trans-isomer as well as an isomer of the naturally occurring ventiloquinone J and its trans-isomer are described in Chapter 3. Starting from 1,2,4,5,8-pentamethoxynaphthalene, the synthesis of which has been described in Chapter 2, ventiloquinone E was prepared in nine steps in an overall yield of 7%. Similarly an isomer of ventiloquinone J was also prepared from 1,2,4,5,8-pentamethoxynaphthalene in ten steps in an overall yield of 6%. In both cases a mixture of cis-and trans-isomers was obtained, a successful resolution of both mixtures was accomplished by thin layer chromatography. By two other methods the trans-isomer of ventiloquinone E could be prepared in either nine steps in an overall yield of 23% or in six steps with an overall yield of 30% starting from the same pentamethoxynaphthalene. 2016-09-28T19:09:04Z 2016-09-28T19:09:04Z 1987 Doctoral Thesis Doctoral PhD http://hdl.handle.net/11427/22000 eng application/pdf Department of Chemistry Faculty of Science University of Cape Town |
| spellingShingle | Naphthoquinone Rifomycin De Koning, Charles Bernard The syntheses of some naturally derived naphthoquinones |
| thesis_degree_str | Doctoral |
| title | The syntheses of some naturally derived naphthoquinones |
| title_full | The syntheses of some naturally derived naphthoquinones |
| title_fullStr | The syntheses of some naturally derived naphthoquinones |
| title_full_unstemmed | The syntheses of some naturally derived naphthoquinones |
| title_short | The syntheses of some naturally derived naphthoquinones |
| title_sort | syntheses of some naturally derived naphthoquinones |
| topic | Naphthoquinone Rifomycin |
| url | http://hdl.handle.net/11427/22000 |
| work_keys_str_mv | AT dekoningcharlesbernard thesynthesesofsomenaturallyderivednaphthoquinones AT dekoningcharlesbernard synthesesofsomenaturallyderivednaphthoquinones |