The dual role of ionic liquid BmimBF₄, precursor of N-heterocyclic carbene and solvent, in the oxidative esterification of aldehydes

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• 作者：Isabella Chiarotto ; Marta Feroci ; Giovanni Sotgiu ; Achille Inesi
• 关键词：Esters ; N-Heterocyclic carbene ; Aldehydes ; Umpolung ; Room temperature ionic liquid ; Oxidations
• 刊名：Tetrahedron
• 出版年：2013
• 出版时间：16 September, 2013
• 年：2013
• 卷：69
• 期：37
• 页码：8088-8095
• 全文大小：1622 K

文摘

Room temperature ionic liquid BmimBF₄ (1-butyl-3-methylimidazolium tetrafluoroborate) has been utilized in the m>Nm>-heterocyclic carbene-catalyzed oxidation of aldehydes to yield esters. In the presence of MnO₂ as oxidant and of DBU and caesium carbonate as bases, aromatic, heteroaromatic and aliphatic esters have been isolated in good to excellent yields. The recyclability of the used ionic liquid along with the excess of inorganic reagents has been proved. The simple and cheap BmimBF₄ ionic liquid played the dual role of precatalyst and solvent. This is the first time that such a reaction has been carried out with an ionic liquid as solvent.