Imidazolium-2-carboxylates (NHC–CO2 adducts, 3) and (benz) imidazolium hydrogen carbonates ([NHC (H)][HCO3], 4) were independently employed as organic precatalysts for various molecular N-heterocyclic carbene (NHC) catalyzed reactions. NHC–CO2 adducts were obtained by carboxylation in THF of related free NHCs (2), while the synthesis of [NHC (H)][HCO3] precursors was directly achieved by anion metathesis of imidazolium halides ( ...
[Gurau, Gabriela; Rodriguez, Hector; Kelley, Steven P.; Janiczek, Peter; Kalb, Roland S.; Rogers, Robin D. Angewandte Chemie - International Edition, 2011 , vol. 50, # 50 p. 12024 - 12026]