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Retro-Diels-Alder routes to 4,5 disubstituted cyclopentenones
Includes bibliographical references ( leaves 78-81)
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| Other Authors: | |
| Format: | Thesis |
| Language: | English |
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Department of Chemistry
2014
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| _version_ | 1867613169324654592 |
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| access_status_str | Open Access |
| author | Kidane, Aklilu Asefaw |
| author2 | Sickle, Eugene S |
| author_browse | Kidane, Aklilu Asefaw Sickle, Eugene S |
| author_facet | Sickle, Eugene S Kidane, Aklilu Asefaw |
| author_sort | Kidane, Aklilu Asefaw |
| collection | Thesis |
| description | Includes bibliographical references ( leaves 78-81) |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/8660 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:31:52.071Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2014 |
| publishDateRange | 2014 |
| publishDateSort | 2014 |
| 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:11427/8660 Retro-Diels-Alder routes to 4,5 disubstituted cyclopentenones Kidane, Aklilu Asefaw Sickle, Eugene S Hunter, Roger Chemistry Includes bibliographical references ( leaves 78-81) Investigation into the synthesis of 4,5-disubstituted cyclopentenones was conducted in light of recent interest on cyclopentenone prostaglandins (PGs) as a new class of anti-viral and anti-inflammatory agents. The strategy involved conjugate addition of various organocuprates to tricyclodecadienone derived from dicyclopentadiene and gave 5-exo-substituted tricyclodecadienones. Attempts to alkylate the kinetic lithium, copper and quaternary ammonium enolates generated from 5-exo-substituted tricyclodecadienones with alkylhalides were unsuccessful. Even in the presence of strong cation solvating hexamethylphosphoramide (HMPA) (±30% co-solvent), lithium enolates proved inert. However, trapping the magnesium enolate generated from the 1, 4-addition of n-butylmagnesium bromide to tricyclodecadienone with aldehydes yielded β-ketols of syn and anti-relative configuration. Due to their labile nature, the β-ketols were dehydrated to their corresponding stable enones. Achiral retro-Diets-Alder reactions were first attempted on 5-exo-substituted tricyclodecadienones using several Lewis-acid catalysts. 4-Substituted-2 cyclopentenones were isolated in good yield and no double bond rearrangement or decomposition was observed. Similar results were also obtained with the dienones generated from dehydration of β-ketols to give αα',ββ'-unsaturated cyclopentadienones in good yield. The synthesis of enantiomerically pure 4- Substituted cyclopentenones and 4- butyl-5-butylidene-cyclopent-2-enone via chiral Lewis-acid catalysed asymmetric retro-Diets-Alder reactions were unsuccessful. Chiral Lewis-acids were prepared in situ from selected Lewis-acids and chiral ligands containing the diol functionality namely BINOL and the TADDOLs. 2014-10-21T06:53:20Z 2014-10-21T06:53:20Z 2005 Master Thesis Masters MSc http://hdl.handle.net/11427/8660 eng application/pdf Department of Chemistry Faculty of Science University of Cape Town |
| spellingShingle | Chemistry Kidane, Aklilu Asefaw Retro-Diels-Alder routes to 4,5 disubstituted cyclopentenones |
| thesis_degree_str | Master's |
| title | Retro-Diels-Alder routes to 4,5 disubstituted cyclopentenones |
| title_full | Retro-Diels-Alder routes to 4,5 disubstituted cyclopentenones |
| title_fullStr | Retro-Diels-Alder routes to 4,5 disubstituted cyclopentenones |
| title_full_unstemmed | Retro-Diels-Alder routes to 4,5 disubstituted cyclopentenones |
| title_short | Retro-Diels-Alder routes to 4,5 disubstituted cyclopentenones |
| title_sort | retro diels alder routes to 4 5 disubstituted cyclopentenones |
| topic | Chemistry |
| url | http://hdl.handle.net/11427/8660 |
| work_keys_str_mv | AT kidaneakliluasefaw retrodielsalderroutesto45disubstitutedcyclopentenones |