Stereochemical aspects of the formation and trifluoroacetolysis of some allylic bis(trimethylsilyl)cyclohexenes

Wickham G. and Kitching W. (1983) Stereochemical aspects of the formation and trifluoroacetolysis of some allylic bis(trimethylsilyl)cyclohexenes. Organometallics, 2 4: 541-547.

Author Wickham G.
Kitching W.
Title Stereochemical aspects of the formation and trifluoroacetolysis of some allylic bis(trimethylsilyl)cyclohexenes
Journal name Organometallics   Check publisher's open access policy
ISSN 0276-7333
Publication date 1983-01-01
Sub-type Article (original research)
Open Access Status Not yet assessed
Volume 2
Issue 4
Start page 541
End page 547
Total pages 7
Subject 1604 Human Geography
1605 Policy and Administration
Abstract The stereochemistry of the 3,4-bis(trimethylsilyl)cyclohexene resulting from disilylation of 1,3-cyclohexadiene is concluded to be cis on the basis of 1H and 13C nuclear magnetic resonance spectra and hydrogenation to Cis-1,2-bis(trimethylsilyl)cyclohexane. The higher boiling cis- and trans-3,6-bis(trimethylsilyl)cyclohexenes could be separated from the above 3,4-isomer but not from each other by careful spinning band distillation. However, the cis,trans compositions of various fractions were established by 13C NMR spectra and chromatographic characteristics. Trifluoroacetolysis (CF3COOD in chloroform) of the cis 3,4-isomer proceeds to yield cyclohexene-d2 as the final product, and analysis of 2H NMR spectra and intermediates demonstrates the importance of a facile 1,2-trimethylsilyl shift in the presumed intermediate ion. Trifluoroacetolysis of the mixtures of the 3,6-disilyl isomers proceeds regiospecifically to yield cyclohex-3-enyltrimethylsilane. A preferred anti mode of attack by the electrophile is indicated for the cis isomer, but syn and anti modes are about equally preferred in the trans isomer. This is attributed to steric congestion by the trimethylsilyl group in the γ-carbon region, hindering anti approach by the electrophile.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import - Archived
 
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Created: Tue, 30 Aug 2016, 14:09:27 EST by System User