Since the discovery of stable carbenes in the last decade of the 20th century, N-heterocyclic carbenes (NHCs) have recently been receiving considerable attention for the catalysis of organic reactions. 1 Many reports on carrying out carbene-catalyzed reactions have been prepared, due to their ability to produce acyl anion equivalents. 2 This feature has been successfully exploited in numerous catalytic reactions, and NHCs also serve as nucleophilic catalysts in several ...
