{"id":{"repo_id":"aachen","oai_identifier":"oai:publications.rwth-aachen.de:59675"},"canonical_url":"https://search.dev.ndltd.org/etd/aachen/oai:publications.rwth-aachen.de:59675","repository":{"repo_id":"aachen","name":"RWTH Aachen University","base_url":"https://publications.rwth-aachen.de/oai2d"},"display":{"title":"Exploring the reactivity of alpha-triorganylsilyl alpha-diazo esters : C-H activation, insertion reactions, and rearrangements","abstract":"The metal-catalyzed reactions of Alpha-triorganylsilyl Alpha-diazo esters have been studied, with an emphasis on: · Dirhodium(II)-catalyzed insertions of Alpha-triorganylsilyl Alpha-diazo esters into activated C-H bonds. · Dirhodium(II)-catalyzed reactions of -triorganylsilyl Alpha-diazo esters with various acyclic and cyclic carbonyl precursors. · The syntheses of Alpha-silyl-substituted Alpha-keto esters, their corresponding hydroxy esters and hydroxy acids, in addition to investigating dirhodium(II)-catalyzed O-H insertion reactions. Insertion of benzyl and ethyl 2-triorganylsilyl 2-diazoacetates into activated C-H bonds adjacent to oxygen, such as in tetrahydrofuran, was possible using dirhodium(II) acetate , albeit in moderate yields (up to 50% yield). When the chiral Davies catalyst was used, benzyl 2-tetrahydro-2-furanyl-2-trimethylsilylacetate was obtained in 58% ee. Ring expanded products were isolated from the reaction of benzyl Alpha-triorganylsilyl Alpha-diazoacetate with oxetane, attributed to a Stevens rearrangement. The dirhodium(II)-catalyzed reaction of Alpha-triorganylsilyl Alpha-diazoacetates proceeded well with various acyclic and cyclic ketones, affording dioxolanones in up to 98% yield. The effect of the structure of the diazo compound on the formation of the dioxolanones was investigated, and various novel silyl-substituted diazo precursors were synthesized for this purpose. A silylated enol ether competes with the formation of a dioxolanone, depending on the electronic and steric properties of the ester functionality. Two routes for the synthesis of Alpha-silyl-substituted Alpha-hydroxy acids were envisioned, comprising dirhodium(II)-catalyzed oxygen transfer and dirhodium(II)-catalyzed O-H insertions. Reactions of Alpha-triorganylsilyl Alpha-diazo esters with propylene oxide afforded 2-silyl-2-oxoacetates in up to 95% yield. These were converted into their corresponding enantiomerically-pure hydroxy acids via reduction using NaBH4, enantiomer separation by preparative HPLC, and palladium-catalyzed hydrogenolytic debenzylation. Alternatively, asymmetric reduction using (R)-Alpine Borane was effective in achieving 2-silyl-2-oxyacetates in up to 91% ee. Various alcohols were effectively inserted into Alpha-triorganylsilyl Alpha-diazo esters, generating 2-silyl-2-oxyacetates in up to 97% yield. Insertion of chiral (R)-and (S)-phenylethanols, followed by separation of the diastereomers, and palladium-catalyzed reduction using molecular hydrogen, made it possible to isolate enantiomerically-pure Alpha-silyl-substituted Alpha-hydroxy acids, circumventing the need for preparative HPLC separation. The best diastereomer ratio (dr) of 91:9 obtained to date was achieved with (1R,2S,5R)-(-)-8-phenylmenthyl (triethylsilyl)diazoacetate and the novel (S)-tetrakis{[2.2]PCp-4-carboxy}dirhodium(II) catalyst in O-H insertions. Finally, enantomerically-pure Alpha-silyl-substituted Alpha-hydroxy acids were tested as ligands in asymmetric catalysis.","abstract_html":"The metal-catalyzed reactions of Alpha-triorganylsilyl Alpha-diazo esters have been studied, with an emphasis on: · Dirhodium(II)-catalyzed insertions of Alpha-triorganylsilyl Alpha-diazo esters into activated C-H bonds. · Dirhodium(II)-catalyzed reactions of -triorganylsilyl Alpha-diazo esters with various acyclic and cyclic carbonyl precursors. · The syntheses of Alpha-silyl-substituted Alpha-keto esters, their corresponding hydroxy esters and hydroxy acids, in addition to investigating dirhodium(II)-catalyzed O-H insertion reactions. Insertion of benzyl and ethyl 2-triorganylsilyl 2-diazoacetates into activated C-H bonds adjacent to oxygen, such as in tetrahydrofuran, was possible using dirhodium(II) acetate , albeit in moderate yields (up to 50% yield). When the chiral Davies catalyst was used, benzyl 2-tetrahydro-2-furanyl-2-trimethylsilylacetate was obtained in 58% ee. Ring expanded products were isolated from the reaction of benzyl Alpha-triorganylsilyl Alpha-diazoacetate with oxetane, attributed to a Stevens rearrangement. The dirhodium(II)-catalyzed reaction of Alpha-triorganylsilyl Alpha-diazoacetates proceeded well with various acyclic and cyclic ketones, affording dioxolanones in up to 98% yield. The effect of the structure of the diazo compound on the formation of the dioxolanones was investigated, and various novel silyl-substituted diazo precursors were synthesized for this purpose. A silylated enol ether competes with the formation of a dioxolanone, depending on the electronic and steric properties of the ester functionality. Two routes for the synthesis of Alpha-silyl-substituted Alpha-hydroxy acids were envisioned, comprising dirhodium(II)-catalyzed oxygen transfer and dirhodium(II)-catalyzed O-H insertions. Reactions of Alpha-triorganylsilyl Alpha-diazo esters with propylene oxide afforded 2-silyl-2-oxoacetates in up to 95% yield. These were converted into their corresponding enantiomerically-pure hydroxy acids via reduction using NaBH4, enantiomer separation by preparative HPLC, and palladium-catalyzed hydrogenolytic debenzylation. Alternatively, asymmetric reduction using (R)-Alpine Borane was effective in achieving 2-silyl-2-oxyacetates in up to 91% ee. Various alcohols were effectively inserted into Alpha-triorganylsilyl Alpha-diazo esters, generating 2-silyl-2-oxyacetates in up to 97% yield. Insertion of chiral (R)-and (S)-phenylethanols, followed by separation of the diastereomers, and palladium-catalyzed reduction using molecular hydrogen, made it possible to isolate enantiomerically-pure Alpha-silyl-substituted Alpha-hydroxy acids, circumventing the need for preparative HPLC separation. The best diastereomer ratio (dr) of 91:9 obtained to date was achieved with (1R,2S,5R)-(-)-8-phenylmenthyl (triethylsilyl)diazoacetate and the novel (S)-tetrakis{[2.2]PCp-4-carboxy}dirhodium(II) catalyst in O-H insertions. Finally, enantomerically-pure Alpha-silyl-substituted Alpha-hydroxy acids were tested as ligands in asymmetric catalysis.","abstract_has_math":false,"creators":["Saladin, Sandra"],"institution":"Publikationsserver der RWTH Aachen University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Bolm, Carsten"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2004,"date_issued":"2004","date_published":"2004","updated_at":"2026-07-30T19:42:48Z","subjects":["info:eu-repo/classification/ddc/540","Ester","Diazoverbindungen","Silylgruppe","Einschiebungsreaktion","Rhodiumkomplexe","Katalysator","Chemie","rhodium","carbenoids","diazo ester","C-H insertion","carbonyl ylides","O-H insertion"],"languages":["eng"],"rights":["info:eu-repo/semantics/openAccess"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-208167%22"],"render_values":[{"text":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-208167%22","href":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-208167%22","code":true}]}]},"links":{"outbound_url":"https://publications.rwth-aachen.de/record/59675","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Bolm, Carsten"]},{"key":"dc:creator","label":"Author","values":["Saladin, Sandra"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:coverage","label":"Dc Coverage","values":["DE"]},{"key":"dc:date","label":"Dc Date","values":["2004"]},{"key":"dc:publisher","label":"Institution","values":["Publikationsserver der RWTH Aachen University"]},{"key":"dc:relation","label":"Dc Relation","values":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-9441"]},{"key":"dc:type","label":"Dc Type","values":["info:eu-repo/semantics/doctoralThesis","info:eu-repo/semantics/publishedVersion"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["info:eu-repo/classification/ddc/540","Ester","Diazoverbindungen","Silylgruppe","Einschiebungsreaktion","Rhodiumkomplexe","Katalysator","Chemie","rhodium","carbenoids","diazo ester","C-H insertion","carbonyl ylides","O-H insertion"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["info:eu-repo/semantics/openAccess"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/record/59675","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-208167%22"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The metal-catalyzed reactions of Alpha-triorganylsilyl Alpha-diazo esters have been studied, with an emphasis on: · Dirhodium(II)-catalyzed insertions of Alpha-triorganylsilyl Alpha-diazo esters into activated C-H bonds. · Dirhodium(II)-catalyzed reactions of -triorganylsilyl Alpha-diazo esters with various acyclic and cyclic carbonyl precursors. · The syntheses of Alpha-silyl-substituted Alpha-keto esters, their corresponding hydroxy esters and hydroxy acids, in addition to investigating dirhodium(II)-catalyzed O-H insertion reactions. Insertion of benzyl and ethyl 2-triorganylsilyl 2-diazoacetates into activated C-H bonds adjacent to oxygen, such as in tetrahydrofuran, was possible using dirhodium(II) acetate , albeit in moderate yields (up to 50% yield). When the chiral Davies catalyst was used, benzyl 2-tetrahydro-2-furanyl-2-trimethylsilylacetate was obtained in 58% ee. Ring expanded products were isolated from the reaction of benzyl Alpha-triorganylsilyl Alpha-diazoacetate with oxetane, attributed to a Stevens rearrangement. The dirhodium(II)-catalyzed reaction of Alpha-triorganylsilyl Alpha-diazoacetates proceeded well with various acyclic and cyclic ketones, affording dioxolanones in up to 98% yield. The effect of the structure of the diazo compound on the formation of the dioxolanones was investigated, and various novel silyl-substituted diazo precursors were synthesized for this purpose. A silylated enol ether competes with the formation of a dioxolanone, depending on the electronic and steric properties of the ester functionality. Two routes for the synthesis of Alpha-silyl-substituted Alpha-hydroxy acids were envisioned, comprising dirhodium(II)-catalyzed oxygen transfer and dirhodium(II)-catalyzed O-H insertions. Reactions of Alpha-triorganylsilyl Alpha-diazo esters with propylene oxide afforded 2-silyl-2-oxoacetates in up to 95% yield. These were converted into their corresponding enantiomerically-pure hydroxy acids via reduction using NaBH4, enantiomer separation by preparative HPLC, and palladium-catalyzed hydrogenolytic debenzylation. Alternatively, asymmetric reduction using (R)-Alpine Borane was effective in achieving 2-silyl-2-oxyacetates in up to 91% ee. Various alcohols were effectively inserted into Alpha-triorganylsilyl Alpha-diazo esters, generating 2-silyl-2-oxyacetates in up to 97% yield. Insertion of chiral (R)-and (S)-phenylethanols, followed by separation of the diastereomers, and palladium-catalyzed reduction using molecular hydrogen, made it possible to isolate enantiomerically-pure Alpha-silyl-substituted Alpha-hydroxy acids, circumventing the need for preparative HPLC separation. The best diastereomer ratio (dr) of 91:9 obtained to date was achieved with (1R,2S,5R)-(-)-8-phenylmenthyl (triethylsilyl)diazoacetate and the novel (S)-tetrakis{[2.2]PCp-4-carboxy}dirhodium(II) catalyst in O-H insertions. Finally, enantomerically-pure Alpha-silyl-substituted Alpha-hydroxy acids were tested as ligands in asymmetric catalysis."]},{"key":"dc:source","label":"Dc Source","values":["Aachen : Publikationsserver der RWTH Aachen University III, 116 S. : graph. Darst. (2004). = Aachen, Techn. Hochsch., Diss., 2004"]},{"key":"dc:title","label":"Title","values":["Exploring the reactivity of alpha-triorganylsilyl alpha-diazo esters : C-H activation, insertion reactions, and rearrangements"]}]}],"canonical_facts":{"dc:contributor":["Bolm, Carsten"],"dc:coverage":["DE"],"dc:creator":["Saladin, Sandra"],"dc:date":["2004"],"dc:description":["The metal-catalyzed reactions of Alpha-triorganylsilyl Alpha-diazo esters have been studied, with an emphasis on: · Dirhodium(II)-catalyzed insertions of Alpha-triorganylsilyl Alpha-diazo esters into activated C-H bonds. · Dirhodium(II)-catalyzed reactions of -triorganylsilyl Alpha-diazo esters with various acyclic and cyclic carbonyl precursors. · The syntheses of Alpha-silyl-substituted Alpha-keto esters, their corresponding hydroxy esters and hydroxy acids, in addition to investigating dirhodium(II)-catalyzed O-H insertion reactions. Insertion of benzyl and ethyl 2-triorganylsilyl 2-diazoacetates into activated C-H bonds adjacent to oxygen, such as in tetrahydrofuran, was possible using dirhodium(II) acetate , albeit in moderate yields (up to 50% yield). When the chiral Davies catalyst was used, benzyl 2-tetrahydro-2-furanyl-2-trimethylsilylacetate was obtained in 58% ee. Ring expanded products were isolated from the reaction of benzyl Alpha-triorganylsilyl Alpha-diazoacetate with oxetane, attributed to a Stevens rearrangement. The dirhodium(II)-catalyzed reaction of Alpha-triorganylsilyl Alpha-diazoacetates proceeded well with various acyclic and cyclic ketones, affording dioxolanones in up to 98% yield. The effect of the structure of the diazo compound on the formation of the dioxolanones was investigated, and various novel silyl-substituted diazo precursors were synthesized for this purpose. A silylated enol ether competes with the formation of a dioxolanone, depending on the electronic and steric properties of the ester functionality. Two routes for the synthesis of Alpha-silyl-substituted Alpha-hydroxy acids were envisioned, comprising dirhodium(II)-catalyzed oxygen transfer and dirhodium(II)-catalyzed O-H insertions. Reactions of Alpha-triorganylsilyl Alpha-diazo esters with propylene oxide afforded 2-silyl-2-oxoacetates in up to 95% yield. These were converted into their corresponding enantiomerically-pure hydroxy acids via reduction using NaBH4, enantiomer separation by preparative HPLC, and palladium-catalyzed hydrogenolytic debenzylation. Alternatively, asymmetric reduction using (R)-Alpine Borane was effective in achieving 2-silyl-2-oxyacetates in up to 91% ee. Various alcohols were effectively inserted into Alpha-triorganylsilyl Alpha-diazo esters, generating 2-silyl-2-oxyacetates in up to 97% yield. Insertion of chiral (R)-and (S)-phenylethanols, followed by separation of the diastereomers, and palladium-catalyzed reduction using molecular hydrogen, made it possible to isolate enantiomerically-pure Alpha-silyl-substituted Alpha-hydroxy acids, circumventing the need for preparative HPLC separation. The best diastereomer ratio (dr) of 91:9 obtained to date was achieved with (1R,2S,5R)-(-)-8-phenylmenthyl (triethylsilyl)diazoacetate and the novel (S)-tetrakis{[2.2]PCp-4-carboxy}dirhodium(II) catalyst in O-H insertions. Finally, enantomerically-pure Alpha-silyl-substituted Alpha-hydroxy acids were tested as ligands in asymmetric catalysis."],"dc:identifier":["https://publications.rwth-aachen.de/record/59675","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-208167%22"],"dc:language":["eng"],"dc:publisher":["Publikationsserver der RWTH Aachen University"],"dc:relation":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-9441"],"dc:rights":["info:eu-repo/semantics/openAccess"],"dc:source":["Aachen : Publikationsserver der RWTH Aachen University III, 116 S. : graph. Darst. (2004). = Aachen, Techn. Hochsch., Diss., 2004"],"dc:subject":["info:eu-repo/classification/ddc/540","Ester","Diazoverbindungen","Silylgruppe","Einschiebungsreaktion","Rhodiumkomplexe","Katalysator","Chemie","rhodium","carbenoids","diazo ester","C-H insertion","carbonyl ylides","O-H insertion"],"dc:title":["Exploring the reactivity of alpha-triorganylsilyl alpha-diazo esters : C-H activation, insertion reactions, and rearrangements"],"dc:type":["info:eu-repo/semantics/doctoralThesis","info:eu-repo/semantics/publishedVersion"]},"updated_at":"2026-07-30T19:42:48Z"}