{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/34528"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/34528","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Asymmetric Lewis base catalysis: I. Lewis base catalyzed halogenation and development of an enantioselective bromocycloetherification reaction; II. enantioselective addition of silyl ketene imines to carbonyl electrophiles","abstract":"Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2012-06-15T13:39:00Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 Thesis-6-12.docx: 11084823 bytes, checksum: 0609048b408ae3adf1f485e3a9dde5d3 (MD5) Burk_Matthew.pdf: 14255171 bytes, checksum: 31badb7e58ce4065eade504990cfba74 (MD5)","abstract_html":"Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2012-06-15T13:39:00Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 Thesis-6-12.docx: 11084823 bytes, checksum: 0609048b408ae3adf1f485e3a9dde5d3 (MD5) Burk_Matthew.pdf: 14255171 bytes, checksum: 31badb7e58ce4065eade504990cfba74 (MD5)","abstract_has_math":false,"creators":["Burk, Matthew"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Chemistry","degree_department":null,"school":null,"contributors":["Denmark, Scott E.","White, Maria C.","van der Donk, Wilfred A.","Rauchfuss, Thomas B."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012-09-18T21:24:13Z","date_published":"2012-09-18T21:24:13Z","updated_at":"2026-07-22T22:25:31Z","subjects":["enantioselective","Halogenation","chlorination","bromination","iodination","chlorolactonization","chloroetherification","chlorocyloetherification","bromolactonization","bromoetherification","bromocycloetherification","iodolactonization","iodoetherification","iodocycloetherification","halonium","haliranium","bromonium","bromiranium","chloronium","chloriranium","solvolysis","racemization","olefin-to-olefin transfer","Lewis base","chiral","chiral Lewis base","Lewis base catalysis","Silicon tetrachloride","silyl ketene imine","aldol","germanium","crossed aldol","kinetics","chiral Bronsted acid"],"languages":["en"],"rights":["Copyright 2012 Matthew Burk"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/34528","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Denmark, Scott E.","White, Maria C.","van der Donk, Wilfred A.","Rauchfuss, Thomas B."]},{"key":"dc:creator","label":"Author","values":["Burk, Matthew"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2012-09-18T21:24:13Z","2014-09-18T10:01:01Z","2012-08"]},{"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":["enantioselective","Halogenation","chlorination","bromination","iodination","chlorolactonization","chloroetherification","chlorocyloetherification","bromolactonization","bromoetherification","bromocycloetherification","iodolactonization","iodoetherification","iodocycloetherification","halonium","haliranium","bromonium","bromiranium","chloronium","chloriranium","solvolysis","racemization","olefin-to-olefin transfer","Lewis base","chiral","chiral Lewis base","Lewis base catalysis","Silicon tetrachloride","silyl ketene imine","aldol","germanium","crossed aldol","kinetics","chiral Bronsted acid"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2012 Matthew Burk"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/34528"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2012-06-15T13:39:00Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 Thesis-6-12.docx: 11084823 bytes, checksum: 0609048b408ae3adf1f485e3a9dde5d3 (MD5) Burk_Matthew.pdf: 14255171 bytes, checksum: 31badb7e58ce4065eade504990cfba74 (MD5)","The stereochemical stability of bromonium and chloronium ions has been investigated in the context of asymmetric catalysis. Bromonium ions have been found to racemize in the presence of olefins by an olefin to olefin transfer process. Chloronium ions do not racemize under the same conditions. The applicability of Lewis base catalysis to bromo- and iodo- cyclization has been investigated. A variety of Lewis bases with sulfur and selenium donors atoms were found to be effective catalysts. Some of these Lewis bases altered the observed ratio of product isomers, implying that they were present in the stereodetermining transition state and therefore had the capacity to produce asymmetric induction despite racemization of the halonium intermediate. Efforts to develop an enantioselective catalyst system based on this principle were unsuccessful, however the combination of an achiral Lewis base and a chiral phosphoric acid enabled a catalytic enantioselective bromoetherification of aryl-pentenols to be developed. Highly enantioselective additions of silyl ketene imines to aromatic aldehydes under SiCl4/chiral Lewis base catalysis were demonstrated. Additions of silyl ketene imines to aliphatic aldehydes were demonstrated with moderate to high enantioselectivity.","Made available in DSpace on 2012-09-18T21:24:13Z (GMT). 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Lewis base catalyzed halogenation and development of an enantioselective bromocycloetherification reaction; II. enantioselective addition of silyl ketene imines to carbonyl electrophiles"]}]}],"canonical_facts":{"dc:contributor":["Denmark, Scott E.","White, Maria C.","van der Donk, Wilfred A.","Rauchfuss, Thomas B."],"dc:creator":["Burk, Matthew"],"dc:date":["2012-09-18T21:24:13Z","2014-09-18T10:01:01Z","2012-08"],"dc:description":["Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2012-06-15T13:39:00Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 Thesis-6-12.docx: 11084823 bytes, checksum: 0609048b408ae3adf1f485e3a9dde5d3 (MD5) Burk_Matthew.pdf: 14255171 bytes, checksum: 31badb7e58ce4065eade504990cfba74 (MD5)","The stereochemical stability of bromonium and chloronium ions has been investigated in the context of asymmetric catalysis. Bromonium ions have been found to racemize in the presence of olefins by an olefin to olefin transfer process. Chloronium ions do not racemize under the same conditions. The applicability of Lewis base catalysis to bromo- and iodo- cyclization has been investigated. A variety of Lewis bases with sulfur and selenium donors atoms were found to be effective catalysts. Some of these Lewis bases altered the observed ratio of product isomers, implying that they were present in the stereodetermining transition state and therefore had the capacity to produce asymmetric induction despite racemization of the halonium intermediate. Efforts to develop an enantioselective catalyst system based on this principle were unsuccessful, however the combination of an achiral Lewis base and a chiral phosphoric acid enabled a catalytic enantioselective bromoetherification of aryl-pentenols to be developed. Highly enantioselective additions of silyl ketene imines to aromatic aldehydes under SiCl4/chiral Lewis base catalysis were demonstrated. Additions of silyl ketene imines to aliphatic aldehydes were demonstrated with moderate to high enantioselectivity.","Made available in DSpace on 2012-09-18T21:24:13Z (GMT). No. of bitstreams: 4 Burk_Matthew.pdf: 14221317 bytes, checksum: 9fb7c2608b7f95b29a082a15ef676936 (MD5) license.txt: 4060 bytes, checksum: e4c690bbba62992a64d8edc64bbff137 (MD5) Thesis-6-26.docx: 11086021 bytes, checksum: 01c0e01afbc635f431824ee65e3f51e2 (MD5) 1_Thesis-6-26.docx: 11086021 bytes, checksum: 01c0e01afbc635f431824ee65e3f51e2 (MD5)","Restriction data tranferred 2014-07-01T11:35:43-05:00 Original Data Group with Access Administrator Release Date: 2014-09-18 16:27:16 UTC Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Item marked as restricted to the 'Administrator' Group (id=1) by Seth Robbins (srobbins@illinois.edu) on 2012-09-18T21:27:21Z Item is restricted until 2014-09-18T21:27:16Z","Limited Restriction Lifted for Item 34802 on 2014-09-18T10:01:01Z."],"dc:identifier":["http://hdl.handle.net/2142/34528"],"dc:language":["en"],"dc:rights":["Copyright 2012 Matthew Burk"],"dc:subject":["enantioselective","Halogenation","chlorination","bromination","iodination","chlorolactonization","chloroetherification","chlorocyloetherification","bromolactonization","bromoetherification","bromocycloetherification","iodolactonization","iodoetherification","iodocycloetherification","halonium","haliranium","bromonium","bromiranium","chloronium","chloriranium","solvolysis","racemization","olefin-to-olefin transfer","Lewis base","chiral","chiral Lewis base","Lewis base catalysis","Silicon tetrachloride","silyl ketene imine","aldol","germanium","crossed aldol","kinetics","chiral Bronsted acid"],"dc:title":["Asymmetric Lewis base catalysis: I. Lewis base catalyzed halogenation and development of an enantioselective bromocycloetherification reaction; II. enantioselective addition of silyl ketene imines to carbonyl electrophiles"],"thesis:degree_discipline":["Chemistry"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:31Z"}