Nucleophilic Carbenes: An Incredible Renaissance

Over thirty years have passed since the pioneering work of H.‐W. Wanzlick on nucleophilic carbenes. A much investigated model is the imidazolidinylidene 1 , which can be generated from dimer 2 and other substrates. The isolation of the stable carbene 3 by A. J. Arduengo III in 1991 sparked incredible developments: addition reactions with increases in the covalency and coordination of the carbene carbon atom dominate the chemistry of such molecules. Recently, Herrmann et al. reported on the use of carbenes as ligands for Pd catalysts.