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Effect of solvent on the inversion of pyramidal sulfonium and selenonium compounds
Author(s) -
Wiegrefe Andreas,
Brinkmann Thomas,
Uzar Horst C.
Publication year - 2001
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.352
Subject(s) - sulfonium , chemistry , diastereomer , solvent , acetonitrile , isomerization , dimethylformamide , nuclear magnetic resonance spectroscopy , solvent effects , walden inversion , stereochemistry , medicinal chemistry , photochemistry , organic chemistry , catalysis , salt (chemistry)
The effects of temperature and solvent on the cis – trans equilibrium and isomerization rates of different cyclic sulfonium and selenonium compounds were investigated by 1 H NMR spectroscopy. A non‐dissociative process was considered to be the most probable mechanism for inversion of configuration. While the temperature had no apparent effect on the equilibrium, in which the trans ‐diastereoisomer dominated in all cases, changing the solvent from dimethylformamide to acetonitrile and to water led to increasing amounts of the cis ‐diastereoisomer. Additionally, the rate of stereomutation of the thiolanium compound was slowed by a factor of 2 and that of the selenolanium compound by a factor of 85. While the pyramidal (vertex) inversion is the most probable mechanism for the sulfonium compounds investigated, some evidence is presented that indicates that the selenonium compound could isomerize via an edge inversion mechanism. Copyright © 2001 John Wiley & Sons, Ltd.