{"id":{"repo_id":"the-open-u","oai_identifier":"oai:oro.open.ac.uk:57266"},"canonical_url":"https://search.dev.ndltd.org/etd/the-open-u/oai:oro.open.ac.uk:57266","repository":{"repo_id":"the-open-u","name":"The Open University","base_url":"https://oro.open.ac.uk/cgi/oai2"},"display":{"title":"Studies on the use of alpha-silyl substituted carbanions in organic synthesis","abstract":"The stereochemical outcome of the Peterson olefination reaction was studied using o(-trimethylsilylbenzyl carbanion and a series of N-aliphatic/aromatic azomethines. All reactions led stereoselectively to trans-olefins in moderate to low yields. The Peterson intermediate was isolated when neopentylideneaniline was used at room temperature. This intermediate, on treatment with base or acid, gives the corresponding trans-alkene and trimethylsilylphenylmethane, thus providing unambiguous evidence for the reversibility of the first step in the olefination process. Silyl-substituted aziridines were synthesised using thermolytic and photolytic reactions between - chloromethyltrimethylsilyl carbanion and N-benzylidenepropylamine or N-benzylideneaniline. The former system gave cis-l-propyl- 2-trimethylsilyl-3-phenylaziridine in moderate yield and the latter gave trans- and cis-1-phenyl-2-trimethylsilyl- 3-phenylaziridine (1: 1) in good yield. These silylaziridines were shown to undergo ring-preserving reactions on alkylation, protonation or desilylation. Further, on reacting with nucleophiles such as hydrogen halides and trimethylsilyl reagents, ring-opened products are formed. The silylaziridines react analogously to silyl epoxides with hydrogen halides; these involve an Sy2 mechanism and lead to the corresponding ring-opened adduct which reacts further to give the protonated derivative. Silylaziridines react with trimethylsilyl iodide to give the trans-ß-silylenamine via an SN1-type process and do not react with trimethylsilyl- chloride, bromide or pseudohalides. Trans- and cis-l-phenyl-2-trimethylsilyl epoxides react with trimethylsilyl halides via an S2 mechanism to give F-haloolefins whereas 1,1-diphenyl-2-trimethylsilyl epoxide reacts with trimethylsilyl halides or pseudohalides to give 1,1-diphenyl-2-trimethylsilylenol ether in quantitative yields via an SN1 process. However, 2-tri\"- ýmethylsilyl-l-oxa&piro[2,5]octane gives the f-pseudohaloolefin via an SN2 mechanism on reaction with trimethylsilyl pseudohalides; tran -/ci-l-phenyl-2-trimethylsilylepoxides give the corresponding olefin with trimethysilyl azide and the corresponding adduct with trimethylsilyl cyanide. The impure isomers, obtained from the reaction between c-l-propyl-2-trimethylsilyl-3-phenylaziridine and (+)-1,1'-binaphthalene-2,2'-diyl hydrogen phosphate were separated by fractional crystallisation and shown to be optically active.","abstract_html":"The stereochemical outcome of the Peterson olefination reaction was studied using o(-trimethylsilylbenzyl carbanion and a series of N-aliphatic/aromatic azomethines. All reactions led stereoselectively to trans-olefins in moderate to low yields. The Peterson intermediate was isolated when neopentylideneaniline was used at room temperature. This intermediate, on treatment with base or acid, gives the corresponding trans-alkene and trimethylsilylphenylmethane, thus providing unambiguous evidence for the reversibility of the first step in the olefination process. Silyl-substituted aziridines were synthesised using thermolytic and photolytic reactions between - chloromethyltrimethylsilyl carbanion and N-benzylidenepropylamine or N-benzylideneaniline. The former system gave cis-l-propyl- 2-trimethylsilyl-3-phenylaziridine in moderate yield and the latter gave trans- and cis-1-phenyl-2-trimethylsilyl- 3-phenylaziridine (1: 1) in good yield. These silylaziridines were shown to undergo ring-preserving reactions on alkylation, protonation or desilylation. Further, on reacting with nucleophiles such as hydrogen halides and trimethylsilyl reagents, ring-opened products are formed. The silylaziridines react analogously to silyl epoxides with hydrogen halides; these involve an Sy2 mechanism and lead to the corresponding ring-opened adduct which reacts further to give the protonated derivative. Silylaziridines react with trimethylsilyl iodide to give the trans-ß-silylenamine via an SN1-type process and do not react with trimethylsilyl- chloride, bromide or pseudohalides. Trans- and cis-l-phenyl-2-trimethylsilyl epoxides react with trimethylsilyl halides via an S2 mechanism to give F-haloolefins whereas 1,1-diphenyl-2-trimethylsilyl epoxide reacts with trimethylsilyl halides or pseudohalides to give 1,1-diphenyl-2-trimethylsilylenol ether in quantitative yields via an SN1 process. However, 2-tri"- ýmethylsilyl-l-oxa&piro[2,5]octane gives the f-pseudohaloolefin via an SN2 mechanism on reaction with trimethylsilyl pseudohalides; tran -/ci-l-phenyl-2-trimethylsilylepoxides give the corresponding olefin with trimethysilyl azide and the corresponding adduct with trimethylsilyl cyanide. The impure isomers, obtained from the reaction between c-l-propyl-2-trimethylsilyl-3-phenylaziridine and (+)-1,1'-binaphthalene-2,2'-diyl hydrogen phosphate were separated by fractional crystallisation and shown to be optically active.","abstract_has_math":false,"creators":["Soobramanien, Marie-Claire Chantal"],"institution":"The Open University","degree_name":"phd","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1989,"date_issued":"1989","date_published":"1989","updated_at":"2026-07-24T05:03:00Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Soobramanien, Marie-Claire Chantal"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["1989"]},{"key":"dc:date.issued","label":"Date","values":["1989"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["The Open University"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://oro.open.ac.uk/57266/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["phd"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://oro.open.ac.uk/57266/1/235325.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The stereochemical outcome of the Peterson olefination reaction was studied using o(-trimethylsilylbenzyl carbanion and a series of N-aliphatic/aromatic azomethines. All reactions led stereoselectively to trans-olefins in moderate to low yields. The Peterson intermediate was isolated when neopentylideneaniline was used at room temperature. This intermediate, on treatment with base or acid, gives the corresponding trans-alkene and trimethylsilylphenylmethane, thus providing unambiguous evidence for the reversibility of the first step in the olefination process. Silyl-substituted aziridines were synthesised using thermolytic and photolytic reactions between - chloromethyltrimethylsilyl carbanion and N-benzylidenepropylamine or N-benzylideneaniline. The former system gave cis-l-propyl- 2-trimethylsilyl-3-phenylaziridine in moderate yield and the latter gave trans- and cis-1-phenyl-2-trimethylsilyl- 3-phenylaziridine (1: 1) in good yield. These silylaziridines were shown to undergo ring-preserving reactions on alkylation, protonation or desilylation. Further, on reacting with nucleophiles such as hydrogen halides and trimethylsilyl reagents, ring-opened products are formed. The silylaziridines react analogously to silyl epoxides with hydrogen halides; these involve an Sy2 mechanism and lead to the corresponding ring-opened adduct which reacts further to give the protonated derivative. Silylaziridines react with trimethylsilyl iodide to give the trans-ß-silylenamine via an SN1-type process and do not react with trimethylsilyl- chloride, bromide or pseudohalides. Trans- and cis-l-phenyl-2-trimethylsilyl epoxides react with trimethylsilyl halides via an S2 mechanism to give F-haloolefins whereas 1,1-diphenyl-2-trimethylsilyl epoxide reacts with trimethylsilyl halides or pseudohalides to give 1,1-diphenyl-2-trimethylsilylenol ether in quantitative yields via an SN1 process. However, 2-tri\"- ýmethylsilyl-l-oxa&piro[2,5]octane gives the f-pseudohaloolefin via an SN2 mechanism on reaction with trimethylsilyl pseudohalides; tran -/ci-l-phenyl-2-trimethylsilylepoxides give the corresponding olefin with trimethysilyl azide and the corresponding adduct with trimethylsilyl cyanide. The impure isomers, obtained from the reaction between c-l-propyl-2-trimethylsilyl-3-phenylaziridine and (+)-1,1'-binaphthalene-2,2'-diyl hydrogen phosphate were separated by fractional crystallisation and shown to be optically active."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Studies on the use of alpha-silyl substituted carbanions in organic synthesis"]}]}],"canonical_facts":{"dc:creator":["Soobramanien, Marie-Claire Chantal"],"dc:date":["1989"],"dc:date.issued":["1989"],"dc:description.abstract":["The stereochemical outcome of the Peterson olefination reaction was studied using o(-trimethylsilylbenzyl carbanion and a series of N-aliphatic/aromatic azomethines. All reactions led stereoselectively to trans-olefins in moderate to low yields. The Peterson intermediate was isolated when neopentylideneaniline was used at room temperature. This intermediate, on treatment with base or acid, gives the corresponding trans-alkene and trimethylsilylphenylmethane, thus providing unambiguous evidence for the reversibility of the first step in the olefination process. Silyl-substituted aziridines were synthesised using thermolytic and photolytic reactions between - chloromethyltrimethylsilyl carbanion and N-benzylidenepropylamine or N-benzylideneaniline. The former system gave cis-l-propyl- 2-trimethylsilyl-3-phenylaziridine in moderate yield and the latter gave trans- and cis-1-phenyl-2-trimethylsilyl- 3-phenylaziridine (1: 1) in good yield. These silylaziridines were shown to undergo ring-preserving reactions on alkylation, protonation or desilylation. Further, on reacting with nucleophiles such as hydrogen halides and trimethylsilyl reagents, ring-opened products are formed. The silylaziridines react analogously to silyl epoxides with hydrogen halides; these involve an Sy2 mechanism and lead to the corresponding ring-opened adduct which reacts further to give the protonated derivative. Silylaziridines react with trimethylsilyl iodide to give the trans-ß-silylenamine via an SN1-type process and do not react with trimethylsilyl- chloride, bromide or pseudohalides. Trans- and cis-l-phenyl-2-trimethylsilyl epoxides react with trimethylsilyl halides via an S2 mechanism to give F-haloolefins whereas 1,1-diphenyl-2-trimethylsilyl epoxide reacts with trimethylsilyl halides or pseudohalides to give 1,1-diphenyl-2-trimethylsilylenol ether in quantitative yields via an SN1 process. However, 2-tri\"- ýmethylsilyl-l-oxa&piro[2,5]octane gives the f-pseudohaloolefin via an SN2 mechanism on reaction with trimethylsilyl pseudohalides; tran -/ci-l-phenyl-2-trimethylsilylepoxides give the corresponding olefin with trimethysilyl azide and the corresponding adduct with trimethylsilyl cyanide. The impure isomers, obtained from the reaction between c-l-propyl-2-trimethylsilyl-3-phenylaziridine and (+)-1,1'-binaphthalene-2,2'-diyl hydrogen phosphate were separated by fractional crystallisation and shown to be optically active."],"dc:format":["application/pdf"],"dc:identifier.uri":["https://oro.open.ac.uk/57266/1/235325.pdf"],"dc:language":["en"],"dc:publisher.institution":["The Open University"],"dc:relation.isreferencedby":["https://oro.open.ac.uk/57266/"],"dc:title":["Studies on the use of alpha-silyl substituted carbanions in organic synthesis"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["phd"]},"updated_at":"2026-07-24T05:03:00Z"}