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A convenient access to 1,2-diferrocenyl-substituted ethylenes via [3 + 2]-cycloelimination of 2-silylated 4,4,5,5-tetrasubstituted 1,3-dithiolanes


Mloston, Grzegorz; Hamera-Faldyga, Roza; Urbaniak, Katarzyna; Weigand, Wolfgang; Heimgartner, Heinz (2018). A convenient access to 1,2-diferrocenyl-substituted ethylenes via [3 + 2]-cycloelimination of 2-silylated 4,4,5,5-tetrasubstituted 1,3-dithiolanes. Journal of Sulfur Chemistry, 39(5):516-524.

Abstract

Ferrocenyl thioketones bearing a hetaryl, phenyl or alkyl group as the second substituent react with (trimethylsilyl)diazomethane at ca. −30°C in THF solution without formation of a stable [3+2]-cycloadduct. After the spontaneous evolution of N2, the corresponding sterically crowded 4,4,5,5-tetrasubstituted 2-silylated 1,3-dithiolanes are formed as products of the second [3 + 2]-cycloaddition of the intermediate thiocarbonyl S-methanide with the starting thioketone. After desilylation by treatment with TBAF, they are converted into the corresponding carbanions, which display different stability depending on the type of substituent. The presence of hetaryl and phenyl groups results in the exclusive formation of 1,2- diferrocenyl ethylenes. In contrast, the presence of methyl groups significantly enhances the stability of the carbanion, which by protonation yields trans-4,5-diferrocenyl-4,5-dimethyl-1,3-dithiolane.

Abstract

Ferrocenyl thioketones bearing a hetaryl, phenyl or alkyl group as the second substituent react with (trimethylsilyl)diazomethane at ca. −30°C in THF solution without formation of a stable [3+2]-cycloadduct. After the spontaneous evolution of N2, the corresponding sterically crowded 4,4,5,5-tetrasubstituted 2-silylated 1,3-dithiolanes are formed as products of the second [3 + 2]-cycloaddition of the intermediate thiocarbonyl S-methanide with the starting thioketone. After desilylation by treatment with TBAF, they are converted into the corresponding carbanions, which display different stability depending on the type of substituent. The presence of hetaryl and phenyl groups results in the exclusive formation of 1,2- diferrocenyl ethylenes. In contrast, the presence of methyl groups significantly enhances the stability of the carbanion, which by protonation yields trans-4,5-diferrocenyl-4,5-dimethyl-1,3-dithiolane.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Uncontrolled Keywords:General Chemistry
Language:English
Date:3 September 2018
Deposited On:19 Jun 2018 11:03
Last Modified:21 Sep 2018 10:25
Publisher:Taylor & Francis
ISSN:1741-5993
Additional Information:This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Sulfur Chemistry on 18.06.2018, available online: http://wwww.tandfonline.com/10.1080/17415993.2018.1485920.
OA Status:Green
Publisher DOI:https://doi.org/10.1080/17415993.2018.1485920
Project Information:
  • : FunderAlexander von Humboldt-Stiftung (Bonn, Germany)
  • : Grant ID
  • : Project TitleInstitutspartnerschaft (Jena-Lodz, project 2018-2020)

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