uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
The First Isolable 2-Silenolate
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry, Organic Chemistry.
2003 In: Angewandte Chemie International Eddition, ISSN 1433-7851, Vol. 42, no 14, 1640-1642 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2003. Vol. 42, no 14, 1640-1642 p.
URN: urn:nbn:se:uu:diva-92334OAI: oai:DiVA.org:uu-92334DiVA: diva2:165372
Available from: 2004-11-03 Created: 2004-11-03Bibliographically approved
In thesis
1. Synthesis and Reactivity Studies of Zwitterionic Silenes and 2-Silenolates
Open this publication in new window or tab >>Synthesis and Reactivity Studies of Zwitterionic Silenes and 2-Silenolates
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes synthesis and reactivity studies of 2-amino-2-siloxysilenes and 2-silenolates, species that are strongly influenced by reversed Si=C bond polarization, i.e. an Siδ-=Cδ+ polarization as compared to the natural Siδ+=Cδ- polarization. Because of the reversed polarization, the 2-amino-2-siloxysilenes are zwitterions and the 2-silenolates are predominantly described by the resonance structure with the negative charge at Si.

Transient zwitterionic 2-amino-2-siloxysilenes are formed thermolytically from carbamylpolysilanes (tris(trimethylsilyl)silylamides) and trapped with 1,3-dienes in nearly quantitative yields. These silenes have structure and reactivity characteristics that differ from earlier studied Si=C bonded compounds. They are thermodynamically stable toward dimerization and react with 1,3-dienes to give exclusively [4+2] cycloadducts. Their reactions with 1,3-dienes proceed in accordance with inverse electron demand (IED) Diels-Alder reactions which is explained by the electron-rich nature of these silenes. The 2-amino-2-siloxysilenes are also less reactive toward alcohols than earlier silenes. Hence, alcohols do not react with 2-amino-2-siloxysilenes but with the silene precursor, the carbamylpolysilanes, leading to alkoxysilanes in high yields. The latter reaction represents a novel base-free synthetic protocol for protection of primary and secondary alcohols with the fluoride resistant but photolabile tris(trimethylsilyl)silyl group.

Another class of formally Si=C bonded compounds, metal 2-silenolates, has been formed in high yields using a novel facile method. Reaction of acyl- and carbamylpolysilanes with potassium tert-butoxide in tetrahydrofurane gives potassium 2-silenolates. The potassium 2-silenolates are stable at room temperature, in contrast to earlier lithium 2-silenolates that degrade rapidly at ambient temperature. The first crystallisable complex of a 2-silenolate was formed and characterized by X-ray crystallography. This 2-silenolate has a pyramidal central Si (ΣSi = 317.8°), and an Si-C single rather than Si=C double bond (r(SiC) = 1.926 Å). The potassium 2-silenolates give exclusively Si alkylated products with alkyl halides and only [4+2] cycloadducts with 1,3-dienes.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2004. 60 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 1034
Organic chemistry, Silicon, Zwitterionic Silene, 2-Silenolate, Diels-Alder Reaction, Silacyclohexene, X-ray Crystallography, Organisk kemi
National Category
Organic Chemistry
urn:nbn:se:uu:diva-4650 (URN)91-554-6080-1 (ISBN)
Public defence
2004-11-26, B41, BMC, Husargatan 3, Uppsala, 13:15
Available from: 2004-11-03 Created: 2004-11-03Bibliographically approved

Open Access in DiVA

No full text

By organisation
Organic Chemistry

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 37 hits
ReferencesLink to record
Permanent link

Direct link