Stereochemical properties of 1,3-bissulfonium salts and 1,3-bissulfonium ylides
作者:
Saul Wolfe,
Peter Chamberlain,
Timothy F. Garrard,
期刊:
Canadian Journal of Chemistry
(NRC Available online 1976)
卷期:
Volume 54,
issue 18
页码: 2847-2861
ISSN:0008-4042
年代: 1976
DOI:10.1139/v76-403
出版商: NRC Research Press
数据来源: NRC
摘要:
Ten acyclic and two cyclic 1,3-bissulfonium bistetrafluoroborates have been synthesized by appropriate modification of the literature procedures for the preparation of such compounds. The acyclic salts are deprotonated readily by one molar-equivalent of potassium hydroxide to give 1,3-bissulfonium ylides. However, under the same conditions, the cyclic salts decompose. Hydrogen exchange experiments reveal that the C2 hydrogens of the cyclic salts are significantly less acidic than the C2 hydrogens of the acyclic salts. The relative acidities of the C2 hydrogens of the cyclic salts depend upon the medium and upon the configuration and conformation of the molecule, and preliminary attempts have been made to associate the kinetic and thermodynamic acidities of these hydrogens with their specific stereochemical environments.Deprotonation of a 1,3-bissulfonium salt is accompanied by a decrease of at least 5 kcal/mol in the barrier to pyramidal inversion at sulfur. However, attempts to establish the static and dynamic behaviour at the carbanionic centre were not successful.
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