1, 3-Dialkylimidazolium-2-carboxylates

Scheme 5 Synthesis of 1,3-dialkylimidazolium salts from the dialkylimidazolium carboxylate...

Recent Applications of the Kolbe-Schmitt Carboxylation Synthesis of l,3-Dialkylimidazolium-2-Carboxylates... 

In comparison, the l,3-dialkylimidazolium-2-carboxylate isolated by Tommasi et al. [27, 40] was revealed to be a more versatile catalyst that allowed the synthesis of benzoylacetic acid from benzophenone and C02 in good yield and under mild conditions (isolated yield 81%). The presence of tetrafluoroborate- or tetraphenyl-borate sodium salts in the reaction was essential, as this allowed the formation of the related 1,3-dialkylimidazolium tetrafluoroborate or tetraphenylborate and the concomitant quantitative trans-carboxylation to sodium benzoylacetate. Likewise, compounds such as acetone, cyclohexanone, and phenylacetonitrile could also be converted with this system to afford the corresponding carboxylate salts (methyl a-cyanophenylacetate) (Scheme 5.8). Following the same general procedure, acetone was carboxylated, being simultaneously the cosolvent and reagent. 

The l,3-dialkylimidazolium-2-carboxylates 8 readily react with dry methanol, benzoylacetone and benzaldehyde in the presence of a stoichiometric amount of NaBF4, KPF6 orNaBPh4 quantitatively affording the corresponding 1,3-dialkylami-dazolium salt according to Scheme 5 [42],... 

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