Demethylation of an Allene Bearing Two Dimethoxythioxanthene Groups by Oxidation via a Vinyl Cation Intermediate

Australian Journal of Chemistry Volume 63 Issue 12 Page 1638-1644 published_at 2010-12-06
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Title ( eng )
Demethylation of an Allene Bearing Two Dimethoxythioxanthene Groups by Oxidation via a Vinyl Cation Intermediate
Creator
Yamaguchi Torahiko
Fuku-en Shin-ichi
Sugawara Shun
Source Title
Australian Journal of Chemistry
Volume 63
Issue 12
Start Page 1638
End Page 1644
Abstract
With the objective of preparing an isolable triplet carbene, we have carried out the oxidation of an allenic compound bearing two thioxanthene moieties (5). Relatively weak oxidants such as Ph3C+BF4 – gave 8, which is the conjugate acid of 5, as a result of a one-electron oxidation followed by hydrogen abstraction, whereas relatively strong oxidants such as SbCl5 furnished a dicationic ketal (9) as a consequence of oxidation and demethylation. Computations on the supposed dicationic intermediate suggest that the singlet state is more stable than the triplet state by 6.7 kcal mol–1 and that the reason for this peculiarity is because the singlet state is essentially a vinyl cation stabilized by a coordinating methoxy group.
NDC
Chemistry [ 430 ]
Language
eng
Resource Type journal article
Publisher
CSIRO Publishing
Date of Issued 2010-12-06
Rights
Copyright (c) 2010 CSIRO
Publish Type Author’s Original
Access Rights open access
Source Identifier
[ISSN] 0004-9425
[DOI] 10.1071/CH10297
[NCID] AA00555860
[DOI] http://dx.doi.org/10.1071/CH10297