Dual Brønsted Acid/Nucleophilic Activation of Carbonylimidazole Derivatives

Carbonylimidazole derivatives have been found to be highly active acylation reagents for esterification and amidation in the presence of pyridinium salts. These reactions are thought to involve both Brønsted acid and nucleophilic catalysis. This mode of activation has been applied to the synthesis of difficult to access oxazolidinones, as well as esters and amides. Finally, the use of pyridinium salts has been shown to accelerate the esterification of carboxylic acids with imidazole carbamates.