{"id":{"repo_id":"cape-town","oai_identifier":"oai:open.uct.ac.za:11427/23105"},"canonical_url":"https://search.dev.ndltd.org/etd/cape-town/oai:open.uct.ac.za:11427/23105","repository":{"repo_id":"cape-town","name":"University of Cape Town","base_url":"https://open.uct.ac.za/oai/request"},"display":{"title":"Synthesis and structure-activity studies of skeletally modified estradiol analogues","abstract":"In the first phase of this investigation, synthetic approaches to skeletally modified variants of 14,17α-ethanoestra-l,3,5(10)-triene-3,17β-diol were examined, with the purpose of determining the influence of configurational inversion at C-8, C-9 or C-13 upon the high oral estrogenicity associated with introduction of a 14, 17-ethano bridge into the estradiol skeleton. 3-Methoxyestra-1,3,5(10)-trien-17-one was converted conventionally into the 13α-isomer, which underwent sequential silyl enol ether formation and dehydrosilylation into 3-methoxy-13α-estra-1,3,5(10), 15-tetraen-17-one, which failed to undergo conversion into the corresponding 3-methoxy-13α-estra-1,3 ,5( 10), 14, 16-pentaen-17-yl acetate required for cycloaddition studies. Hydrogenation of 3-methoxyestra-1,3,5( 10),8, 14-pentaen-17β-yl acetate afforded 3-methoxy-8α-estra-1,3 ,5(10)-trien-17β-yl acetate, which was converted into 3-methoxy-8α-estra-1,3 ,5(10), 14, 16-pentaen-17-yl acetate. Cycloaddition with phenyl vinyl sulfone gave a mixture of products, which was converted into the desired 14,17α-ethano-8α-estra- 1,3,5(10)-triene-3, 17β-diol, by a hydrogenation, desulfonylation, deprotection reaction sequence. The unexpectedly complex result for the cycloaddition reaction was interpreted with the assistance of other cycloaddition reactions of the Δ¹⁴,¹⁶-dienyl acetate. 17,17-Ethylenedioxy-3-methoxy-9β-estra-l ,3,5(10)-trien-11-one was readily prepared from estrone using conventional methodology. Deoxygenation followed by standard functional group manipulation afforded 3-methoxy-9β-estra-1 ,3 ,5(10)-trien-17-one. As a result of the poor overall yield, the optimisation of a number of steps in this reaction sequence was investigated. Despite some improvement in the yields, subsequent conversion into the target, 14, 17a-ethano-9β-estra-1,3 ,5(10)-triene-3, 17β-diol was not synthetically useful. However, dehydrogenation of 14, 17α-ethanoestra-1,3,5(10)-triene-3, 17β-diol followed by standard functional group modification gave 14, 17 a-ethanoestra-1,3 ,5(10),9(11)-tetraene- 3, 17β-diyl diacetate, hydrogenation of which afforded 14, 17α-ethano-9β-estra-1 ,3,5(10)triene-3, 17β-diol, after conventional deprotection, in moderate yield.","abstract_html":"In the first phase of this investigation, synthetic approaches to skeletally modified variants of 14,17α-ethanoestra-l,3,5(10)-triene-3,17β-diol were examined, with the purpose of determining the influence of configurational inversion at C-8, C-9 or C-13 upon the high oral estrogenicity associated with introduction of a 14, 17-ethano bridge into the estradiol skeleton. 3-Methoxyestra-1,3,5(10)-trien-17-one was converted conventionally into the 13α-isomer, which underwent sequential silyl enol ether formation and dehydrosilylation into 3-methoxy-13α-estra-1,3,5(10), 15-tetraen-17-one, which failed to undergo conversion into the corresponding 3-methoxy-13α-estra-1,3 ,5( 10), 14, 16-pentaen-17-yl acetate required for cycloaddition studies. Hydrogenation of 3-methoxyestra-1,3,5( 10),8, 14-pentaen-17β-yl acetate afforded 3-methoxy-8α-estra-1,3 ,5(10)-trien-17β-yl acetate, which was converted into 3-methoxy-8α-estra-1,3 ,5(10), 14, 16-pentaen-17-yl acetate. Cycloaddition with phenyl vinyl sulfone gave a mixture of products, which was converted into the desired 14,17α-ethano-8α-estra- 1,3,5(10)-triene-3, 17β-diol, by a hydrogenation, desulfonylation, deprotection reaction sequence. The unexpectedly complex result for the cycloaddition reaction was interpreted with the assistance of other cycloaddition reactions of the Δ¹⁴,¹⁶-dienyl acetate. 17,17-Ethylenedioxy-3-methoxy-9β-estra-l ,3,5(10)-trien-11-one was readily prepared from estrone using conventional methodology. Deoxygenation followed by standard functional group manipulation afforded 3-methoxy-9β-estra-1 ,3 ,5(10)-trien-17-one. As a result of the poor overall yield, the optimisation of a number of steps in this reaction sequence was investigated. Despite some improvement in the yields, subsequent conversion into the target, 14, 17a-ethano-9β-estra-1,3 ,5(10)-triene-3, 17β-diol was not synthetically useful. However, dehydrogenation of 14, 17α-ethanoestra-1,3,5(10)-triene-3, 17β-diol followed by standard functional group modification gave 14, 17 a-ethanoestra-1,3 ,5(10),9(11)-tetraene- 3, 17β-diyl diacetate, hydrogenation of which afforded 14, 17α-ethano-9β-estra-1 ,3,5(10)triene-3, 17β-diol, after conventional deprotection, in moderate yield.","abstract_has_math":false,"creators":["De Koning, Pieter David"],"institution":"Department of Chemistry","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Bull, James R"],"committee_chairs":[],"committee_members":[],"year":1997,"date_issued":"1997","date_published":"1997","updated_at":"2026-07-22T22:22:47Z","subjects":[],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11427/23105","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Bull, James R"]},{"key":"dc:creator","label":"Author","values":["De Koning, Pieter David"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2017-01-25T14:40:22Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2017-01-25T14:40:22Z"]},{"key":"dc:date.issued","label":"Date","values":["1997"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Department of Chemistry"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Cape Town"]},{"key":"dc:type","label":"Dc Type","values":["Doctoral Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["PhD"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11427/23105"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["In the first phase of this investigation, synthetic approaches to skeletally modified variants of 14,17α-ethanoestra-l,3,5(10)-triene-3,17β-diol were examined, with the purpose of determining the influence of configurational inversion at C-8, C-9 or C-13 upon the high oral estrogenicity associated with introduction of a 14, 17-ethano bridge into the estradiol skeleton. 3-Methoxyestra-1,3,5(10)-trien-17-one was converted conventionally into the 13α-isomer, which underwent sequential silyl enol ether formation and dehydrosilylation into 3-methoxy-13α-estra-1,3,5(10), 15-tetraen-17-one, which failed to undergo conversion into the corresponding 3-methoxy-13α-estra-1,3 ,5( 10), 14, 16-pentaen-17-yl acetate required for cycloaddition studies. Hydrogenation of 3-methoxyestra-1,3,5( 10),8, 14-pentaen-17β-yl acetate afforded 3-methoxy-8α-estra-1,3 ,5(10)-trien-17β-yl acetate, which was converted into 3-methoxy-8α-estra-1,3 ,5(10), 14, 16-pentaen-17-yl acetate. Cycloaddition with phenyl vinyl sulfone gave a mixture of products, which was converted into the desired 14,17α-ethano-8α-estra- 1,3,5(10)-triene-3, 17β-diol, by a hydrogenation, desulfonylation, deprotection reaction sequence. The unexpectedly complex result for the cycloaddition reaction was interpreted with the assistance of other cycloaddition reactions of the Δ¹⁴,¹⁶-dienyl acetate. 17,17-Ethylenedioxy-3-methoxy-9β-estra-l ,3,5(10)-trien-11-one was readily prepared from estrone using conventional methodology. Deoxygenation followed by standard functional group manipulation afforded 3-methoxy-9β-estra-1 ,3 ,5(10)-trien-17-one. As a result of the poor overall yield, the optimisation of a number of steps in this reaction sequence was investigated. Despite some improvement in the yields, subsequent conversion into the target, 14, 17a-ethano-9β-estra-1,3 ,5(10)-triene-3, 17β-diol was not synthetically useful. However, dehydrogenation of 14, 17α-ethanoestra-1,3,5(10)-triene-3, 17β-diol followed by standard functional group modification gave 14, 17 a-ethanoestra-1,3 ,5(10),9(11)-tetraene- 3, 17β-diyl diacetate, hydrogenation of which afforded 14, 17α-ethano-9β-estra-1 ,3,5(10)triene-3, 17β-diol, after conventional deprotection, in moderate yield."]},{"key":"dc:title","label":"Title","values":["Synthesis and structure-activity studies of skeletally modified estradiol analogues"]}]}],"canonical_facts":{"dc:contributor.advisor":["Bull, James R"],"dc:creator":["De Koning, Pieter David"],"dc:date.accessioned":["2017-01-25T14:40:22Z"],"dc:date.available":["2017-01-25T14:40:22Z"],"dc:date.issued":["1997"],"dc:description.abstract":["In the first phase of this investigation, synthetic approaches to skeletally modified variants of 14,17α-ethanoestra-l,3,5(10)-triene-3,17β-diol were examined, with the purpose of determining the influence of configurational inversion at C-8, C-9 or C-13 upon the high oral estrogenicity associated with introduction of a 14, 17-ethano bridge into the estradiol skeleton. 3-Methoxyestra-1,3,5(10)-trien-17-one was converted conventionally into the 13α-isomer, which underwent sequential silyl enol ether formation and dehydrosilylation into 3-methoxy-13α-estra-1,3,5(10), 15-tetraen-17-one, which failed to undergo conversion into the corresponding 3-methoxy-13α-estra-1,3 ,5( 10), 14, 16-pentaen-17-yl acetate required for cycloaddition studies. Hydrogenation of 3-methoxyestra-1,3,5( 10),8, 14-pentaen-17β-yl acetate afforded 3-methoxy-8α-estra-1,3 ,5(10)-trien-17β-yl acetate, which was converted into 3-methoxy-8α-estra-1,3 ,5(10), 14, 16-pentaen-17-yl acetate. Cycloaddition with phenyl vinyl sulfone gave a mixture of products, which was converted into the desired 14,17α-ethano-8α-estra- 1,3,5(10)-triene-3, 17β-diol, by a hydrogenation, desulfonylation, deprotection reaction sequence. The unexpectedly complex result for the cycloaddition reaction was interpreted with the assistance of other cycloaddition reactions of the Δ¹⁴,¹⁶-dienyl acetate. 17,17-Ethylenedioxy-3-methoxy-9β-estra-l ,3,5(10)-trien-11-one was readily prepared from estrone using conventional methodology. Deoxygenation followed by standard functional group manipulation afforded 3-methoxy-9β-estra-1 ,3 ,5(10)-trien-17-one. As a result of the poor overall yield, the optimisation of a number of steps in this reaction sequence was investigated. Despite some improvement in the yields, subsequent conversion into the target, 14, 17a-ethano-9β-estra-1,3 ,5(10)-triene-3, 17β-diol was not synthetically useful. However, dehydrogenation of 14, 17α-ethanoestra-1,3,5(10)-triene-3, 17β-diol followed by standard functional group modification gave 14, 17 a-ethanoestra-1,3 ,5(10),9(11)-tetraene- 3, 17β-diyl diacetate, hydrogenation of which afforded 14, 17α-ethano-9β-estra-1 ,3,5(10)triene-3, 17β-diol, after conventional deprotection, in moderate yield."],"dc:identifier.uri":["http://hdl.handle.net/11427/23105"],"dc:language.iso":["eng"],"dc:publisher.department":["Department of Chemistry"],"dc:publisher.institution":["University of Cape Town"],"dc:title":["Synthesis and structure-activity studies of skeletally modified estradiol analogues"],"dc:type":["Doctoral Thesis"],"dc:type.qualificationlevel":["Doctoral"],"dc:type.qualificationname":["PhD"]},"updated_at":"2026-07-22T22:22:47Z"}