{"id":{"repo_id":"cape-town","oai_identifier":"oai:open.uct.ac.za:11427/41366"},"canonical_url":"https://search.dev.ndltd.org/etd/cape-town/oai:open.uct.ac.za:11427/41366","repository":{"repo_id":"cape-town","name":"University of Cape Town","base_url":"https://open.uct.ac.za/oai/request"},"display":{"title":"Chiral acyl radicals generated by visible light enable stereoselective access to 3,3-disubstituted oxindoles: application toward the synthesis of (–)- and (+)-physovenine","abstract":"Radical species serve as powerful tools for carbon-carbon bond formation in synthetic organic chemistry. Such species can be formed in an efficient and environmentally friendly manner by way of photoredox catalysis, which uses a photocatalyst in conjunction with visible light (typically) to generate the necessary environment for radical generation under extremely mild conditions. This work outlines the development of a novel imidazolidinone-derived acyl radical, generated under photoredox catalysis, and its application toward the stereoselective synthesis of 3,3- disubstituted oxindoles via an additional-cyclisation cascade sequence to acrylamide precursors. 6 oxindoles were produced in up to 85% yield, with moderate diastereoselectivity of up to 2.2:1, but which could be easily separated by standard chromatography to yield pure diastereomers. Mechanistic studies, by virtue of TEMPO-trapping experiments provided strong support for the existence of the proposed acyl-radical, and further synthetic utility of the research was demonstrated in formal synthesis of the natural product (–)-physovenine, a member of the biologically active cyclotryptamine alkaloids.","abstract_html":"Radical species serve as powerful tools for carbon-carbon bond formation in synthetic organic chemistry. Such species can be formed in an efficient and environmentally friendly manner by way of photoredox catalysis, which uses a photocatalyst in conjunction with visible light (typically) to generate the necessary environment for radical generation under extremely mild conditions. This work outlines the development of a novel imidazolidinone-derived acyl radical, generated under photoredox catalysis, and its application toward the stereoselective synthesis of 3,3- disubstituted oxindoles via an additional-cyclisation cascade sequence to acrylamide precursors. 6 oxindoles were produced in up to 85% yield, with moderate diastereoselectivity of up to 2.2:1, but which could be easily separated by standard chromatography to yield pure diastereomers. Mechanistic studies, by virtue of TEMPO-trapping experiments provided strong support for the existence of the proposed acyl-radical, and further synthetic utility of the research was demonstrated in formal synthesis of the natural product (–)-physovenine, a member of the biologically active cyclotryptamine alkaloids.","abstract_has_math":false,"creators":["Späth, Josef"],"institution":"Department of Chemistry","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Petersen, Wade","Hunter, Roger"],"committee_chairs":[],"committee_members":[],"year":2024,"date_issued":"2024","date_published":"2024","updated_at":"2026-07-22T22:22:51Z","subjects":["chemistry"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11427/41366","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Petersen, Wade","Hunter, Roger"]},{"key":"dc:creator","label":"Author","values":["Späth, Josef"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2025-04-08T11:25:58Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2025-04-08T11:25:58Z"]},{"key":"dc:date.issued","label":"Date","values":["2024"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Department of Chemistry"]},{"key":"dc:type","label":"Dc Type","values":["Thesis / Dissertation"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Masters","MSc"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["chemistry"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11427/41366"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Radical species serve as powerful tools for carbon-carbon bond formation in synthetic organic chemistry. Such species can be formed in an efficient and environmentally friendly manner by way of photoredox catalysis, which uses a photocatalyst in conjunction with visible light (typically) to generate the necessary environment for radical generation under extremely mild conditions. This work outlines the development of a novel imidazolidinone-derived acyl radical, generated under photoredox catalysis, and its application toward the stereoselective synthesis of 3,3- disubstituted oxindoles via an additional-cyclisation cascade sequence to acrylamide precursors. 6 oxindoles were produced in up to 85% yield, with moderate diastereoselectivity of up to 2.2:1, but which could be easily separated by standard chromatography to yield pure diastereomers. Mechanistic studies, by virtue of TEMPO-trapping experiments provided strong support for the existence of the proposed acyl-radical, and further synthetic utility of the research was demonstrated in formal synthesis of the natural product (–)-physovenine, a member of the biologically active cyclotryptamine alkaloids."]},{"key":"dc:title","label":"Title","values":["Chiral acyl radicals generated by visible light enable stereoselective access to 3,3-disubstituted oxindoles: application toward the synthesis of (–)- and (+)-physovenine"]}]}],"canonical_facts":{"dc:contributor.advisor":["Petersen, Wade","Hunter, Roger"],"dc:creator":["Späth, Josef"],"dc:date.accessioned":["2025-04-08T11:25:58Z"],"dc:date.available":["2025-04-08T11:25:58Z"],"dc:date.issued":["2024"],"dc:description.abstract":["Radical species serve as powerful tools for carbon-carbon bond formation in synthetic organic chemistry. Such species can be formed in an efficient and environmentally friendly manner by way of photoredox catalysis, which uses a photocatalyst in conjunction with visible light (typically) to generate the necessary environment for radical generation under extremely mild conditions. This work outlines the development of a novel imidazolidinone-derived acyl radical, generated under photoredox catalysis, and its application toward the stereoselective synthesis of 3,3- disubstituted oxindoles via an additional-cyclisation cascade sequence to acrylamide precursors. 6 oxindoles were produced in up to 85% yield, with moderate diastereoselectivity of up to 2.2:1, but which could be easily separated by standard chromatography to yield pure diastereomers. Mechanistic studies, by virtue of TEMPO-trapping experiments provided strong support for the existence of the proposed acyl-radical, and further synthetic utility of the research was demonstrated in formal synthesis of the natural product (–)-physovenine, a member of the biologically active cyclotryptamine alkaloids."],"dc:identifier.uri":["http://hdl.handle.net/11427/41366"],"dc:publisher.department":["Department of Chemistry"],"dc:subject":["chemistry"],"dc:title":["Chiral acyl radicals generated by visible light enable stereoselective access to 3,3-disubstituted oxindoles: application toward the synthesis of (–)- and (+)-physovenine"],"dc:type":["Thesis / Dissertation"],"dc:type.qualificationlevel":["Masters","MSc"]},"updated_at":"2026-07-22T22:22:51Z"}