Base-catalyzed Effective C2-Amidation of Azolium Salts Using Isocyanates under Mild Conditions.

An unprecedented base-catalyzed hydroarylation of isocyanates with azolium salts was developed, which follows a simple reaction pathway and provided facile access to diverse C2-amidated azolium salts under mild conditions. Importantly, this methodology can also be applied for the successive C2-amidation of a bisimidazolium salt with two different isocyanates to provide the corresponding unsymmetrically substituted bisamide derivatives. Notably, the obtained amidated salts can also serve as a prominent carbene surrogate for the synthesis of metal-NHC complexes.