{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/16830"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/16830","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Preparative and mechanistic aspects of palladium-catalyzed cross-coupling reactions of alkali-metal arylsilanolates","abstract":"The development of alkali-metal arylsilanolates as notable organometallic reagents for the preparation of biaryls has been realized through in depth mechanistic and preparative studies. The alkali-metal salts (potassium and sodium) of a large number of arylsilanols undergo smooth cross-coupling with a wide range of aromatic bromides and chlorides. The critical feature for the success of these coupling reactions and their considerable scope is the use of bis(tri-tert-butylphosphine)palladium. Additionally, these studies have identified the use of phosphine oxides (e.g. triphenylphosphine oxide) as useful ligands for palladium-catalyzed cross-coupling reactions. This serendipitous discovery was founded on kinetic experiments which revealed a significant rate enhancement employing these species as ligands for palladium. Later, these ligands were implemented in the reaction of arylsilanolates for the preparation of biaryl products. The mechanism of palladium-catalyzed cross-coupling reactions of alkali-metal organosilanolates has also been investigated. Under catalysis by (t-Bu3P)2Pd, the coupling with aryl bromides displays the following rate equation: rate = kobs[R3SiOK]0[ArylBr]0, with kobs = k[(t-Bu3P)2Pd]0.98. An independent study of the individual steps of the catalytic cycle has revealed a dual mechanistic pathway. The transmetalation can occur by a thermal process via an 8-Si-4 intermediate without the need for anionic activation. Additionally, arylsilanolates can serve as activators for transmetalation via a hypervalent 10-Si-5 siliconate intermediate. The independent isolation of the putative arylpalladium(II) arylsilanolate intermediate has confirmed the generation of the Pd-O-Si linkage prior to transmetalation. The unique opportunity to isolate a pretransmetalation intermediate has allowed the transmetalation step to be further refined through a detailed Hammett analysis which has demonstrated that increased electron-density about the arylsilanolate nucleophile increases the rate of coupling. Furthermore, a number of alkenyl- and arylsilanolate pretransmetalation species have been isolated with various ligands in attempts to identify the critical features of the cross-coupling of this class of organonucleophiles.","abstract_html":"The development of alkali-metal arylsilanolates as notable organometallic reagents for the preparation of biaryls has been realized through in depth mechanistic and preparative studies. The alkali-metal salts (potassium and sodium) of a large number of arylsilanols undergo smooth cross-coupling with a wide range of aromatic bromides and chlorides. The critical feature for the success of these coupling reactions and their considerable scope is the use of bis(tri-tert-butylphosphine)palladium. Additionally, these studies have identified the use of phosphine oxides (e.g. triphenylphosphine oxide) as useful ligands for palladium-catalyzed cross-coupling reactions. This serendipitous discovery was founded on kinetic experiments which revealed a significant rate enhancement employing these species as ligands for palladium. Later, these ligands were implemented in the reaction of arylsilanolates for the preparation of biaryl products. The mechanism of palladium-catalyzed cross-coupling reactions of alkali-metal organosilanolates has also been investigated. Under catalysis by (t-Bu3P)2Pd, the coupling with aryl bromides displays the following rate equation: rate = kobs[R3SiOK]0[ArylBr]0, with kobs = k[(t-Bu3P)2Pd]0.98. An independent study of the individual steps of the catalytic cycle has revealed a dual mechanistic pathway. The transmetalation can occur by a thermal process via an 8-Si-4 intermediate without the need for anionic activation. Additionally, arylsilanolates can serve as activators for transmetalation via a hypervalent 10-Si-5 siliconate intermediate. The independent isolation of the putative arylpalladium(II) arylsilanolate intermediate has confirmed the generation of the Pd-O-Si linkage prior to transmetalation. The unique opportunity to isolate a pretransmetalation intermediate has allowed the transmetalation step to be further refined through a detailed Hammett analysis which has demonstrated that increased electron-density about the arylsilanolate nucleophile increases the rate of coupling. Furthermore, a number of alkenyl- and arylsilanolate pretransmetalation species have been isolated with various ligands in attempts to identify the critical features of the cross-coupling of this class of organonucleophiles.","abstract_has_math":false,"creators":["Smith, Russell C."],"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.","Hartwig, John F.","Hergenrother, Paul J.","Girolami, Gregory S."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2010,"date_issued":"2010-08-20T17:59:12Z","date_published":"2010-08-20T17:59:12Z","updated_at":"2026-07-22T22:25:09Z","subjects":["arylsilanolates","biaryls","mechanism","palladium"],"languages":["en"],"rights":["Copyright 2010 Russell C. Smith"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/16830","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Denmark, Scott E.","Hartwig, John F.","Hergenrother, Paul J.","Girolami, Gregory S."]},{"key":"dc:creator","label":"Author","values":["Smith, Russell C."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2010-08-20T17:59:12Z","2010-08"]},{"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":["arylsilanolates","biaryls","mechanism","palladium"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2010 Russell C. Smith"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/16830"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The development of alkali-metal arylsilanolates as notable organometallic reagents for the preparation of biaryls has been realized through in depth mechanistic and preparative studies. The alkali-metal salts (potassium and sodium) of a large number of arylsilanols undergo smooth cross-coupling with a wide range of aromatic bromides and chlorides. The critical feature for the success of these coupling reactions and their considerable scope is the use of bis(tri-tert-butylphosphine)palladium. Additionally, these studies have identified the use of phosphine oxides (e.g. triphenylphosphine oxide) as useful ligands for palladium-catalyzed cross-coupling reactions. This serendipitous discovery was founded on kinetic experiments which revealed a significant rate enhancement employing these species as ligands for palladium. Later, these ligands were implemented in the reaction of arylsilanolates for the preparation of biaryl products. The mechanism of palladium-catalyzed cross-coupling reactions of alkali-metal organosilanolates has also been investigated. Under catalysis by (t-Bu3P)2Pd, the coupling with aryl bromides displays the following rate equation: rate = kobs[R3SiOK]0[ArylBr]0, with kobs = k[(t-Bu3P)2Pd]0.98. An independent study of the individual steps of the catalytic cycle has revealed a dual mechanistic pathway. The transmetalation can occur by a thermal process via an 8-Si-4 intermediate without the need for anionic activation. Additionally, arylsilanolates can serve as activators for transmetalation via a hypervalent 10-Si-5 siliconate intermediate. The independent isolation of the putative arylpalladium(II) arylsilanolate intermediate has confirmed the generation of the Pd-O-Si linkage prior to transmetalation. The unique opportunity to isolate a pretransmetalation intermediate has allowed the transmetalation step to be further refined through a detailed Hammett analysis which has demonstrated that increased electron-density about the arylsilanolate nucleophile increases the rate of coupling. Furthermore, a number of alkenyl- and arylsilanolate pretransmetalation species have been isolated with various ligands in attempts to identify the critical features of the cross-coupling of this class of organonucleophiles.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2010-07-06T14:24:52Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 3 Smith_Russell.pdf: 27286513 bytes, checksum: a87e02f08ab4bed099025ca7ba658c3a (MD5) Smith_Russell_thesis_front matter.doc: 88576 bytes, checksum: 9777b1ac2b5d89b542d1069842aa57e4 (MD5) Smith_Russell_thesis.doc: 26628608 bytes, checksum: 59f153f1816202b756bcb8d3c9e58647 (MD5)","Made available in DSpace on 2010-08-20T17:59:12Z (GMT). No. of bitstreams: 6 Smith_Russell.pdf: 27259965 bytes, checksum: 5c07a1856a8ecdbb8b2a4248fa9ffba3 (MD5) 1_Smith_Russell.pdf: 27286513 bytes, checksum: a87e02f08ab4bed099025ca7ba658c3a (MD5) 2_Smith_Russell.pdf: 27217647 bytes, checksum: 4e5f070628088487566c549b355b2064 (MD5) Smith_Russell_thesis_front matter.doc: 88576 bytes, checksum: 9777b1ac2b5d89b542d1069842aa57e4 (MD5) Smith_Russell_thesis.doc: 26628608 bytes, checksum: 59f153f1816202b756bcb8d3c9e58647 (MD5) license.txt: 4063 bytes, checksum: 2125c6ec4f4073a0a88bd646c91fedd7 (MD5)"]},{"key":"dc:title","label":"Title","values":["Preparative and mechanistic aspects of palladium-catalyzed cross-coupling reactions of alkali-metal arylsilanolates"]}]}],"canonical_facts":{"dc:contributor":["Denmark, Scott E.","Hartwig, John F.","Hergenrother, Paul J.","Girolami, Gregory S."],"dc:creator":["Smith, Russell C."],"dc:date":["2010-08-20T17:59:12Z","2010-08"],"dc:description":["The development of alkali-metal arylsilanolates as notable organometallic reagents for the preparation of biaryls has been realized through in depth mechanistic and preparative studies. The alkali-metal salts (potassium and sodium) of a large number of arylsilanols undergo smooth cross-coupling with a wide range of aromatic bromides and chlorides. The critical feature for the success of these coupling reactions and their considerable scope is the use of bis(tri-tert-butylphosphine)palladium. Additionally, these studies have identified the use of phosphine oxides (e.g. triphenylphosphine oxide) as useful ligands for palladium-catalyzed cross-coupling reactions. This serendipitous discovery was founded on kinetic experiments which revealed a significant rate enhancement employing these species as ligands for palladium. Later, these ligands were implemented in the reaction of arylsilanolates for the preparation of biaryl products. The mechanism of palladium-catalyzed cross-coupling reactions of alkali-metal organosilanolates has also been investigated. Under catalysis by (t-Bu3P)2Pd, the coupling with aryl bromides displays the following rate equation: rate = kobs[R3SiOK]0[ArylBr]0, with kobs = k[(t-Bu3P)2Pd]0.98. An independent study of the individual steps of the catalytic cycle has revealed a dual mechanistic pathway. The transmetalation can occur by a thermal process via an 8-Si-4 intermediate without the need for anionic activation. Additionally, arylsilanolates can serve as activators for transmetalation via a hypervalent 10-Si-5 siliconate intermediate. The independent isolation of the putative arylpalladium(II) arylsilanolate intermediate has confirmed the generation of the Pd-O-Si linkage prior to transmetalation. The unique opportunity to isolate a pretransmetalation intermediate has allowed the transmetalation step to be further refined through a detailed Hammett analysis which has demonstrated that increased electron-density about the arylsilanolate nucleophile increases the rate of coupling. Furthermore, a number of alkenyl- and arylsilanolate pretransmetalation species have been isolated with various ligands in attempts to identify the critical features of the cross-coupling of this class of organonucleophiles.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2010-07-06T14:24:52Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 3 Smith_Russell.pdf: 27286513 bytes, checksum: a87e02f08ab4bed099025ca7ba658c3a (MD5) Smith_Russell_thesis_front matter.doc: 88576 bytes, checksum: 9777b1ac2b5d89b542d1069842aa57e4 (MD5) Smith_Russell_thesis.doc: 26628608 bytes, checksum: 59f153f1816202b756bcb8d3c9e58647 (MD5)","Made available in DSpace on 2010-08-20T17:59:12Z (GMT). No. of bitstreams: 6 Smith_Russell.pdf: 27259965 bytes, checksum: 5c07a1856a8ecdbb8b2a4248fa9ffba3 (MD5) 1_Smith_Russell.pdf: 27286513 bytes, checksum: a87e02f08ab4bed099025ca7ba658c3a (MD5) 2_Smith_Russell.pdf: 27217647 bytes, checksum: 4e5f070628088487566c549b355b2064 (MD5) Smith_Russell_thesis_front matter.doc: 88576 bytes, checksum: 9777b1ac2b5d89b542d1069842aa57e4 (MD5) Smith_Russell_thesis.doc: 26628608 bytes, checksum: 59f153f1816202b756bcb8d3c9e58647 (MD5) license.txt: 4063 bytes, checksum: 2125c6ec4f4073a0a88bd646c91fedd7 (MD5)"],"dc:identifier":["http://hdl.handle.net/2142/16830"],"dc:language":["en"],"dc:rights":["Copyright 2010 Russell C. Smith"],"dc:subject":["arylsilanolates","biaryls","mechanism","palladium"],"dc:title":["Preparative and mechanistic aspects of palladium-catalyzed cross-coupling reactions of alkali-metal arylsilanolates"],"thesis:degree_discipline":["Chemistry"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:09Z"}