Anionic N-heterocyclic carbenes by decarboxylation of sydnone-4-carboxylates

Ana Luiza Lücke, Sascha Wiechmann, Tyll Freese, Martin Nieger, Tamás Földes, I. Pápai, Mimoza Gjikaj, Arnold Adam, Andreas Schmidt

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Unstable N-heterocyclic carbenes can be masked and stabilized as pseudo-cross-conjugated hetarenium-carboxylates which decarboxylate on warming. This study deals with the decarboxylation of carboxylates of mesoionic compounds to generate anionic N-heterocyclic carbenes. Lithium sydnone-4-carboxylates were therefore prepared via 4-bromosydnones by halogen-lithium exchange with nBuLi and subsequent treatment with carbon dioxide. Protonation gave the corresponding sydnone-4-carboxylic acids. Thermogravimetric measurements in addition to temperature dependent IR spectroscopy proved the decarboxylation of lithium sydnone-4-carboxylates and formation of the corresponding sydnone anions which can be represented as anionic N-heterocyclic carbenes. In DMSO-d6 solution, water favors the decarboxylation. Calculations have been performed to elucidate the mechanism of the decarboxylation in the absence and presence of water.

Original languageEnglish
Pages (from-to)2092-2099
Number of pages8
JournalTetrahedron
Volume74
Issue number16
DOIs
Publication statusPublished - Apr 19 2018

Fingerprint

Sydnones
Decarboxylation
Lithium
Halogens
Water
Protonation
Carboxylic Acids
Dimethyl Sulfoxide
Carbon Dioxide
Anions
Infrared spectroscopy
Spectrum Analysis
Temperature
carbene

Keywords

  • Decarboxylation
  • IR spectroscopy
  • Mesoionic compound
  • N-heterocyclic carbene
  • Sydnone

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

Cite this

Lücke, A. L., Wiechmann, S., Freese, T., Nieger, M., Földes, T., Pápai, I., ... Schmidt, A. (2018). Anionic N-heterocyclic carbenes by decarboxylation of sydnone-4-carboxylates. Tetrahedron, 74(16), 2092-2099. https://doi.org/10.1016/j.tet.2018.03.019

Anionic N-heterocyclic carbenes by decarboxylation of sydnone-4-carboxylates. / Lücke, Ana Luiza; Wiechmann, Sascha; Freese, Tyll; Nieger, Martin; Földes, Tamás; Pápai, I.; Gjikaj, Mimoza; Adam, Arnold; Schmidt, Andreas.

In: Tetrahedron, Vol. 74, No. 16, 19.04.2018, p. 2092-2099.

Research output: Contribution to journalArticle

Lücke, AL, Wiechmann, S, Freese, T, Nieger, M, Földes, T, Pápai, I, Gjikaj, M, Adam, A & Schmidt, A 2018, 'Anionic N-heterocyclic carbenes by decarboxylation of sydnone-4-carboxylates', Tetrahedron, vol. 74, no. 16, pp. 2092-2099. https://doi.org/10.1016/j.tet.2018.03.019
Lücke AL, Wiechmann S, Freese T, Nieger M, Földes T, Pápai I et al. Anionic N-heterocyclic carbenes by decarboxylation of sydnone-4-carboxylates. Tetrahedron. 2018 Apr 19;74(16):2092-2099. https://doi.org/10.1016/j.tet.2018.03.019
Lücke, Ana Luiza ; Wiechmann, Sascha ; Freese, Tyll ; Nieger, Martin ; Földes, Tamás ; Pápai, I. ; Gjikaj, Mimoza ; Adam, Arnold ; Schmidt, Andreas. / Anionic N-heterocyclic carbenes by decarboxylation of sydnone-4-carboxylates. In: Tetrahedron. 2018 ; Vol. 74, No. 16. pp. 2092-2099.
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