Anionic N-heterocyclic carbenes by decarboxylation of sydnone-4-carboxylates
| Autor: | Ana-Luiza Lücke, Tamás Földes, Sascha Wiechmann, Arnold Adam, Martin Nieger, Mimoza Gjikaj, Andreas Schmidt, Imre Pápai, Tyll Freese |
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| Přispěvatelé: | Department of Chemistry |
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Thermogravimetric analysis
RING Decarboxylation 116 Chemical sciences chemistry.chemical_element Infrared spectroscopy Protonation Sydnone 010402 general chemistry 01 natural sciences Biochemistry Medicinal chemistry chemistry.chemical_compound HYDROGEN-BOND CHEMISTRY Drug Discovery NUCLEOPHILIC CARBENES YLIDES 010405 organic chemistry Hydrogen bond Organic Chemistry Mesoionic article CONJUGATED MESOMERIC BETAINES Mesoionic compound BORANE ADDUCTS LEWIS PAIR 0104 chemical sciences chemistry 13. Climate action IR spectroscopy ddc:540 CYCLOADDITION REACTIONS Lithium Mesoionic compound -- N-heterocyclic carbene -- Sydnone -- Decarboxylation -- IR spectroscopy SIGMA-SYDNONYL COMPLEXES N-heterocyclic carbene |
| Popis: | 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. (C) 2018 Elsevier Ltd. All rights reserved. |
| Databáze: | OpenAIRE |
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