Formylation of electron-rich aromatic rings mediated by dichloromethyl methyl ether and TiCl4: scope and limitations
The conventional electrophilic intramolecular aromatic substitution pathway proposed by Cresp et al. [J. Chem. Soc., Perkin Trans. 1 1973, 340 345] is confirmed by the observed products of phenolic formylation mediated by TiCl4. However, when the nucleophilic path is quenched by appropriate ligand m...
| Autores: | , , , , , |
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| Tipo de documento: | artigo |
| Estado: | Versão publicada |
| Data de publicação: | 2015 |
| País: | España |
| Recursos: | Universidad de Barcelona |
| Repositório: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/152116 |
| Acesso em linha: | https://hdl.handle.net/2445/152116 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Aldehids Hidrocarburs aromàtics policíclics Clorurs Aldehydes Polycyclic aromatic hydrocarbons Chlorides |
| Resumo: | The conventional electrophilic intramolecular aromatic substitution pathway proposed by Cresp et al. [J. Chem. Soc., Perkin Trans. 1 1973, 340 345] is confirmed by the observed products of phenolic formylation mediated by TiCl4. However, when the nucleophilic path is quenched by appropriate ligand modification, the initial equilibria between the possible neutral complexes of TiCl4 with 3,5-dimethoxy-phenol and/or diethyl ether lead to different stable diradical intermediates induced by valence tautomerism that provide valuable activated reagents. Some of these species have been detected by EPR, characterized theoretically and captured by TEMPO, thus providing a consistent mechanism for the reaction with one or more equivalents of TEMPO per phenol. |
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