{"id":{"repo_id":"ubc","oai_identifier":"oai:circle.library.ubc.ca:2429/1430"},"canonical_url":"https://search.dev.ndltd.org/etd/ubc/oai:circle.library.ubc.ca:2429/1430","repository":{"repo_id":"ubc","name":"University of British Columbia","base_url":"http://circle.library.ubc.ca/oai/request"},"display":{"title":"Synthesis of Limonoid and Steroidal intermediates","abstract":"The cyclopentyl intermediate 4 is an easily obtained, highly enantiopure starting material for the synthesis of numerous triterpenoids. Prepared from (+)-endo-3-bromocamphor (2) in a four-step sequence, 4 has been converted into two advanced triterpenoid intermediates. In an eleven-step sequence 4 was transformed into the bicyclic intermediate (42) that could be used in an enantiospecific approach to the limonoids. The enone 42 was subsequently dialkylated in a regio- and stereoselective manner to produce the intermediate 45. Removal of the silyl protecting group followed by oxidation and acid-catalysed annulation produced the tricyclic enone 53. Structure 53 represents a highly advanced ent-limonoid intermediate with correct relative and absolute stereochemistry with obvious similarities to limonoids such as ent-azadirone (6). Further investigations illustrated 4's utility in the synthesis of the steroidal hydrindane system. Using an analogous pathway 4 was again converted to a bicyclic enone 104 in eight steps. Regiospecific alkylation followed by medium pressure hydrogenation and epimerization yielded the hydrindane 110. Extensive NMR analysis of this compound was used to provide conclusive evidence of 110's absolute stereochemistry. This route is therefore potentially useful in an approach to natural products such as 1α, 25-Dihydroxyvitamin D₃ (58).","abstract_html":"The cyclopentyl intermediate 4 is an easily obtained, highly enantiopure starting material for the synthesis of numerous triterpenoids. Prepared from (+)-endo-3-bromocamphor (2) in a four-step sequence, 4 has been converted into two advanced triterpenoid intermediates. In an eleven-step sequence 4 was transformed into the bicyclic intermediate (42) that could be used in an enantiospecific approach to the limonoids. The enone 42 was subsequently dialkylated in a regio- and stereoselective manner to produce the intermediate 45. Removal of the silyl protecting group followed by oxidation and acid-catalysed annulation produced the tricyclic enone 53. Structure 53 represents a highly advanced ent-limonoid intermediate with correct relative and absolute stereochemistry with obvious similarities to limonoids such as ent-azadirone (6). Further investigations illustrated 4's utility in the synthesis of the steroidal hydrindane system. Using an analogous pathway 4 was again converted to a bicyclic enone 104 in eight steps. Regiospecific alkylation followed by medium pressure hydrogenation and epimerization yielded the hydrindane 110. Extensive NMR analysis of this compound was used to provide conclusive evidence of 110's absolute stereochemistry. This route is therefore potentially useful in an approach to natural products such as 1α, 25-Dihydroxyvitamin D₃ (58).","abstract_has_math":false,"creators":["Richardson, Scott Rowand"],"institution":"University of British Columbia","degree_name":"Master of Science - MSc","degree_level":"master's","degree_discipline":"Chemistry","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1993,"date_issued":"1993","date_published":"1993","updated_at":"2026-07-24T05:07:26Z","subjects":[],"languages":["eng"],"rights":["For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2429/1430","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Richardson, Scott Rowand"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["1993"]},{"key":"dc:publisher","label":"Institution","values":["University of British Columbia"]},{"key":"dc:type","label":"Dc Type","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemistry"]},{"key":"thesis:degree_level","label":"Degree Level","values":["master's"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science - MSc"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of British Columbia"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["For non-commercial purposes only, such as research, private study and education. 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Removal of the silyl protecting group followed by oxidation and acid-catalysed annulation produced the tricyclic enone 53. Structure 53 represents a highly advanced ent-limonoid intermediate with correct relative and absolute stereochemistry with obvious similarities to limonoids such as ent-azadirone (6). Further investigations illustrated 4's utility in the synthesis of the steroidal hydrindane system. Using an analogous pathway 4 was again converted to a bicyclic enone 104 in eight steps. Regiospecific alkylation followed by medium pressure hydrogenation and epimerization yielded the hydrindane 110. Extensive NMR analysis of this compound was used to provide conclusive evidence of 110's absolute stereochemistry. This route is therefore potentially useful in an approach to natural products such as 1α, 25-Dihydroxyvitamin D₃ (58)."]},{"key":"dc:format","label":"Dc Format","values":["3425881","application/pdf"]},{"key":"dc:title","label":"Title","values":["Synthesis of Limonoid and Steroidal intermediates"]}]}],"canonical_facts":{"dc:creator":["Richardson, Scott Rowand"],"dc:date":["1993"],"dc:description":["The cyclopentyl intermediate 4 is an easily obtained, highly enantiopure starting material for the synthesis of numerous triterpenoids. Prepared from (+)-endo-3-bromocamphor (2) in a four-step sequence, 4 has been converted into two advanced triterpenoid intermediates. In an eleven-step sequence 4 was transformed into the bicyclic intermediate (42) that could be used in an enantiospecific approach to the limonoids. The enone 42 was subsequently dialkylated in a regio- and stereoselective manner to produce the intermediate 45. Removal of the silyl protecting group followed by oxidation and acid-catalysed annulation produced the tricyclic enone 53. Structure 53 represents a highly advanced ent-limonoid intermediate with correct relative and absolute stereochemistry with obvious similarities to limonoids such as ent-azadirone (6). Further investigations illustrated 4's utility in the synthesis of the steroidal hydrindane system. Using an analogous pathway 4 was again converted to a bicyclic enone 104 in eight steps. Regiospecific alkylation followed by medium pressure hydrogenation and epimerization yielded the hydrindane 110. Extensive NMR analysis of this compound was used to provide conclusive evidence of 110's absolute stereochemistry. This route is therefore potentially useful in an approach to natural products such as 1α, 25-Dihydroxyvitamin D₃ (58)."],"dc:format":["3425881","application/pdf"],"dc:identifier":["http://hdl.handle.net/2429/1430","http://circle.library.ubc.ca/bitstream/2429/1430/1/ubc_1993_fall_richardson_scott.pdf"],"dc:language":["eng"],"dc:publisher":["University of British Columbia"],"dc:rights":["For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."],"dc:title":["Synthesis of Limonoid and Steroidal intermediates"],"dc:type":["Text"],"thesis:degree_discipline":["Chemistry"],"thesis:degree_level":["master's"],"thesis:degree_name":["Master of Science - MSc"],"thesis:institution_name":["University of British Columbia"]},"updated_at":"2026-07-24T05:07:26Z"}