{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/70291"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/70291","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Silicon-Directed Nazarov Cyclization","abstract":"A new variation of the Nazarov cyclization has been developed in which an organosilyl group beta to a divinyl ketone directs the incipient double bond to the thermodynamically less stable position. Two general methods for preparing beta-silyl divinyl ketones are reported. Ferric chloride induces cyclization under mild conditions in good yields with predictable and complete control over the position of the double bond. An extensive study of the scope, mechanism, and stereochemical outcome of the reaction is also reported. This variant of the Nazarov cyclization is quite general for the preparation or annelation of cyclopentenones. The observed effects of substituents on reaction rate can be explained by a rate-limiting cationic electrocyclization. The degree of stereochemical control was modest (ca. 3:1) in forming the indenone ring system. The substituent in the major isomer was always cis to the ring fusion protons. Thorough spectroscopic and conformational analysis revealed that divergent senses of electrocyclization were responsible for the observed products. Additional experiments suggest that steric, rather stereoelectronic forces control the sense of cyclization. A qualitative description of the nature of reactive intermediates in the silicon-directed Nazarov reaction is proposed as well as an explanation for the remarkable efficacy of ferric chloride for inducing the reaction. Silyl substitution has been shown to retard the reaction.","abstract_html":"A new variation of the Nazarov cyclization has been developed in which an organosilyl group beta to a divinyl ketone directs the incipient double bond to the thermodynamically less stable position. Two general methods for preparing beta-silyl divinyl ketones are reported. Ferric chloride induces cyclization under mild conditions in good yields with predictable and complete control over the position of the double bond. An extensive study of the scope, mechanism, and stereochemical outcome of the reaction is also reported. This variant of the Nazarov cyclization is quite general for the preparation or annelation of cyclopentenones. The observed effects of substituents on reaction rate can be explained by a rate-limiting cationic electrocyclization. The degree of stereochemical control was modest (ca. 3:1) in forming the indenone ring system. The substituent in the major isomer was always cis to the ring fusion protons. Thorough spectroscopic and conformational analysis revealed that divergent senses of electrocyclization were responsible for the observed products. Additional experiments suggest that steric, rather stereoelectronic forces control the sense of cyclization. A qualitative description of the nature of reactive intermediates in the silicon-directed Nazarov reaction is proposed as well as an explanation for the remarkable efficacy of ferric chloride for inducing the reaction. Silyl substitution has been shown to retard the reaction.","abstract_has_math":false,"creators":["Jones, Todd Kevin"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Chemistry","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-12-15T23:18:25Z","date_published":"2014-12-15T23:18:25Z","updated_at":"2026-07-22T22:26:02Z","subjects":["Chemistry, Organic"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(UMI)AAI8511622"],"render_values":[{"text":"(UMI)AAI8511622","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/70291","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Jones, Todd Kevin"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2014-12-15T23:18:25Z","10000-01-01","1985"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemistry"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Chemistry, Organic"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/70291","(UMI)AAI8511622"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["A new variation of the Nazarov cyclization has been developed in which an organosilyl group beta to a divinyl ketone directs the incipient double bond to the thermodynamically less stable position. Two general methods for preparing beta-silyl divinyl ketones are reported. Ferric chloride induces cyclization under mild conditions in good yields with predictable and complete control over the position of the double bond. An extensive study of the scope, mechanism, and stereochemical outcome of the reaction is also reported. This variant of the Nazarov cyclization is quite general for the preparation or annelation of cyclopentenones. The observed effects of substituents on reaction rate can be explained by a rate-limiting cationic electrocyclization. The degree of stereochemical control was modest (ca. 3:1) in forming the indenone ring system. The substituent in the major isomer was always cis to the ring fusion protons. Thorough spectroscopic and conformational analysis revealed that divergent senses of electrocyclization were responsible for the observed products. Additional experiments suggest that steric, rather stereoelectronic forces control the sense of cyclization. A qualitative description of the nature of reactive intermediates in the silicon-directed Nazarov reaction is proposed as well as an explanation for the remarkable efficacy of ferric chloride for inducing the reaction. Silyl substitution has been shown to retard the reaction.","Made available in DSpace on 2014-12-15T23:18:25Z (GMT). No. of bitstreams: 1 8511622.pdf: 4919043 bytes, checksum: 7db40958b51ddba9f5436910441dab86 (MD5) Previous issue date: 1985","Embargo set by: Seth Robbins for item 70457 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","156 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985."]},{"key":"dc:title","label":"Title","values":["Silicon-Directed Nazarov Cyclization"]}]}],"canonical_facts":{"dc:creator":["Jones, Todd Kevin"],"dc:date":["2014-12-15T23:18:25Z","10000-01-01","1985"],"dc:description":["A new variation of the Nazarov cyclization has been developed in which an organosilyl group beta to a divinyl ketone directs the incipient double bond to the thermodynamically less stable position. Two general methods for preparing beta-silyl divinyl ketones are reported. Ferric chloride induces cyclization under mild conditions in good yields with predictable and complete control over the position of the double bond. An extensive study of the scope, mechanism, and stereochemical outcome of the reaction is also reported. This variant of the Nazarov cyclization is quite general for the preparation or annelation of cyclopentenones. The observed effects of substituents on reaction rate can be explained by a rate-limiting cationic electrocyclization. The degree of stereochemical control was modest (ca. 3:1) in forming the indenone ring system. The substituent in the major isomer was always cis to the ring fusion protons. Thorough spectroscopic and conformational analysis revealed that divergent senses of electrocyclization were responsible for the observed products. Additional experiments suggest that steric, rather stereoelectronic forces control the sense of cyclization. A qualitative description of the nature of reactive intermediates in the silicon-directed Nazarov reaction is proposed as well as an explanation for the remarkable efficacy of ferric chloride for inducing the reaction. Silyl substitution has been shown to retard the reaction.","Made available in DSpace on 2014-12-15T23:18:25Z (GMT). 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