{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/20828"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/20828","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Scope and stereochemistry of carbon-carbon bond formation via addition of carbon nucleophiles to nitrones","abstract":"The scope and stereochemistry of nucleophilic addition of Grignard reagents and silyl ketene acetals to acyclic and cyclic nitrones have been studied. A 4:1 selectivity favoring axial addition was observed in the reactions of cis-3,5-dimethyl-2,3,4,5-tetrahydropyridine N-oxide with both methyl and phenyl Grignard reagents and the silyl ketene acetal of t-butyl acetate. However, similar additions of carbon nucleophiles to 4-t-butyl-2,3,4,5-tetrahydropyridine N-oxide afforded only the trans isomer from axial addition in moderate yields (60-68%). The stereoselectivity in these endocyclic nitrone additions can be explained by a stereoelectronic effect which favors axial approach of the nucleophile. Acyclic nitrones reacted with crotyl Grignard reagent to give different diastereoselectivity depending on the substrates. Syn-anti selectivities ranging from 7:1 to 1:3 were observed in the reactions of acyclic nitrones with E-silyl ketene acetals of t-butyl propionate. The addition of Grignard reagents to nitrones of glyoxylate esters provides a direct method for the preparation of N-($\\alpha$-hydroxylamino) esters. The scope of this addition reaction was surveyed with a diversity of substrates and nucleophiles. Primary, secondary, tertiary, vinyl, and aryl Grignard reagents generally gave good yields (55-81%) in the nitrone addition reactions. High diastereoselectivity (13-15:1) was observed in Grignard addition to nitrones of (1R, 2S, 5R)-phenylmenthyl esters. The facial bias of the reaction can be explained by a chelation model. N-Deoxygenation of N,N-dialkylhydroxylamines was achieved by reduction with trivalent phosphorus reagents via desulfurization of their thionocarbonate derivatives. The mechanism of the desulfurization reaction has been studied by a double labelling experiment provide an intermolecular pathway. Alternatively, reduction of the N,N-dialkylhydroxylamine adducts was accomplished by either lithium-ammonia or catalytic hydrogenation of their hydroxyamino carbonates. N-Deoxygenation of silyl ketene acetal adducts was effected by catalytic hydrogenation using palladium as a catalyst.","abstract_html":"The scope and stereochemistry of nucleophilic addition of Grignard reagents and silyl ketene acetals to acyclic and cyclic nitrones have been studied. A 4:1 selectivity favoring axial addition was observed in the reactions of cis-3,5-dimethyl-2,3,4,5-tetrahydropyridine N-oxide with both methyl and phenyl Grignard reagents and the silyl ketene acetal of t-butyl acetate. However, similar additions of carbon nucleophiles to 4-t-butyl-2,3,4,5-tetrahydropyridine N-oxide afforded only the trans isomer from axial addition in moderate yields (60-68%). The stereoselectivity in these endocyclic nitrone additions can be explained by a stereoelectronic effect which favors axial approach of the nucleophile. Acyclic nitrones reacted with crotyl Grignard reagent to give different diastereoselectivity depending on the substrates. Syn-anti selectivities ranging from 7:1 to 1:3 were observed in the reactions of acyclic nitrones with E-silyl ketene acetals of t-butyl propionate. The addition of Grignard reagents to nitrones of glyoxylate esters provides a direct method for the preparation of N-(<span class=\"etd-inline-math\">&alpha;</span>-hydroxylamino) esters. The scope of this addition reaction was surveyed with a diversity of substrates and nucleophiles. Primary, secondary, tertiary, vinyl, and aryl Grignard reagents generally gave good yields (55-81%) in the nitrone addition reactions. High diastereoselectivity (13-15:1) was observed in Grignard addition to nitrones of (1R, 2S, 5R)-phenylmenthyl esters. The facial bias of the reaction can be explained by a chelation model. N-Deoxygenation of N,N-dialkylhydroxylamines was achieved by reduction with trivalent phosphorus reagents via desulfurization of their thionocarbonate derivatives. The mechanism of the desulfurization reaction has been studied by a double labelling experiment provide an intermolecular pathway. Alternatively, reduction of the N,N-dialkylhydroxylamine adducts was accomplished by either lithium-ammonia or catalytic hydrogenation of their hydroxyamino carbonates. N-Deoxygenation of silyl ketene acetal adducts was effected by catalytic hydrogenation using palladium as a catalyst.","abstract_has_math":true,"creators":["Tao, Ming"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Chemistry","degree_department":null,"school":null,"contributors":["Coates, Robert M."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-05-07T12:50:30Z","date_published":"2011-05-07T12:50:30Z","updated_at":"2026-07-22T22:25:16Z","subjects":["Chemistry, Organic"],"languages":["eng"],"rights":["Copyright 1992 Tao, Ming"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9215895","(UMI)AAI9215895"],"render_values":[{"text":"AAI9215895","href":null,"code":true},{"text":"(UMI)AAI9215895","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/20828","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Coates, Robert M."]},{"key":"dc:creator","label":"Author","values":["Tao, Ming"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-05-07T12:50:30Z","10000-01-01","1992"]},{"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":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1992 Tao, Ming"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9215895","(UMI)AAI9215895","http://hdl.handle.net/2142/20828"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The scope and stereochemistry of nucleophilic addition of Grignard reagents and silyl ketene acetals to acyclic and cyclic nitrones have been studied. A 4:1 selectivity favoring axial addition was observed in the reactions of cis-3,5-dimethyl-2,3,4,5-tetrahydropyridine N-oxide with both methyl and phenyl Grignard reagents and the silyl ketene acetal of t-butyl acetate. However, similar additions of carbon nucleophiles to 4-t-butyl-2,3,4,5-tetrahydropyridine N-oxide afforded only the trans isomer from axial addition in moderate yields (60-68%). The stereoselectivity in these endocyclic nitrone additions can be explained by a stereoelectronic effect which favors axial approach of the nucleophile. Acyclic nitrones reacted with crotyl Grignard reagent to give different diastereoselectivity depending on the substrates. Syn-anti selectivities ranging from 7:1 to 1:3 were observed in the reactions of acyclic nitrones with E-silyl ketene acetals of t-butyl propionate. The addition of Grignard reagents to nitrones of glyoxylate esters provides a direct method for the preparation of N-($\\alpha$-hydroxylamino) esters. The scope of this addition reaction was surveyed with a diversity of substrates and nucleophiles. Primary, secondary, tertiary, vinyl, and aryl Grignard reagents generally gave good yields (55-81%) in the nitrone addition reactions. High diastereoselectivity (13-15:1) was observed in Grignard addition to nitrones of (1R, 2S, 5R)-phenylmenthyl esters. The facial bias of the reaction can be explained by a chelation model. N-Deoxygenation of N,N-dialkylhydroxylamines was achieved by reduction with trivalent phosphorus reagents via desulfurization of their thionocarbonate derivatives. The mechanism of the desulfurization reaction has been studied by a double labelling experiment provide an intermolecular pathway. Alternatively, reduction of the N,N-dialkylhydroxylamine adducts was accomplished by either lithium-ammonia or catalytic hydrogenation of their hydroxyamino carbonates. N-Deoxygenation of silyl ketene acetal adducts was effected by catalytic hydrogenation using palladium as a catalyst.","Made available in DSpace on 2011-05-07T12:50:30Z (GMT). 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A 4:1 selectivity favoring axial addition was observed in the reactions of cis-3,5-dimethyl-2,3,4,5-tetrahydropyridine N-oxide with both methyl and phenyl Grignard reagents and the silyl ketene acetal of t-butyl acetate. However, similar additions of carbon nucleophiles to 4-t-butyl-2,3,4,5-tetrahydropyridine N-oxide afforded only the trans isomer from axial addition in moderate yields (60-68%). The stereoselectivity in these endocyclic nitrone additions can be explained by a stereoelectronic effect which favors axial approach of the nucleophile. Acyclic nitrones reacted with crotyl Grignard reagent to give different diastereoselectivity depending on the substrates. Syn-anti selectivities ranging from 7:1 to 1:3 were observed in the reactions of acyclic nitrones with E-silyl ketene acetals of t-butyl propionate. The addition of Grignard reagents to nitrones of glyoxylate esters provides a direct method for the preparation of N-($\\alpha$-hydroxylamino) esters. The scope of this addition reaction was surveyed with a diversity of substrates and nucleophiles. Primary, secondary, tertiary, vinyl, and aryl Grignard reagents generally gave good yields (55-81%) in the nitrone addition reactions. High diastereoselectivity (13-15:1) was observed in Grignard addition to nitrones of (1R, 2S, 5R)-phenylmenthyl esters. The facial bias of the reaction can be explained by a chelation model. N-Deoxygenation of N,N-dialkylhydroxylamines was achieved by reduction with trivalent phosphorus reagents via desulfurization of their thionocarbonate derivatives. The mechanism of the desulfurization reaction has been studied by a double labelling experiment provide an intermolecular pathway. Alternatively, reduction of the N,N-dialkylhydroxylamine adducts was accomplished by either lithium-ammonia or catalytic hydrogenation of their hydroxyamino carbonates. N-Deoxygenation of silyl ketene acetal adducts was effected by catalytic hydrogenation using palladium as a catalyst.","Made available in DSpace on 2011-05-07T12:50:30Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9215895.pdf: 6586993 bytes, checksum: 047501aa0d30bf179037c21f25bc39c0 (MD5) Previous issue date: 1992","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:46:34Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:20:53-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission","ETDs are only available to UIUC Users without author permission","U of I Only"],"dc:identifier":["AAI9215895","(UMI)AAI9215895","http://hdl.handle.net/2142/20828"],"dc:language":["eng"],"dc:rights":["Copyright 1992 Tao, Ming"],"dc:subject":["Chemistry, Organic"],"dc:title":["Scope and stereochemistry of carbon-carbon bond formation via addition of carbon nucleophiles to nitrones"],"dc:type":["text"],"thesis:degree_discipline":["Chemistry"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:16Z"}