On the mechanism of phenolic formylation mediated by TiCl4 complexes: existence of diradical intermediates induced by valence tautomerism
| Autor: | Heras, Carlos, Ramos Tomillero, Iván, Caballero Puig, Marc, Paradís Bas, Marta, Nicolás Galindo, Ernesto, Albericio Palomera, Fernando, Moreira, Ibério de Pinho Ribeiro, Bofill i Villà, Josep M. |
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| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | Dipòsit Digital de la UB Universidad de Barcelona |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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