Generation of N-Heterocyclic Carbenes by Metal-Mediated Coupling of Propargylamine and Isocyanides

摘要

Nowadays,there is a great deal of interest in the chemistry of N-heterocyclic carbenes of imidazol-2-ylidene type (Arduengo's carbenes).An important reason for the encouragement of this chemistry is the application of transition metal complexes bearing N-heterocyclic carbenes as ancillary ligands in homogeneous catalysis.Methods for synthesizing these complexes mainly consist of direct reaction of either the stable Arduengo's carbene or the imidazolium salt with the appropriate metal fragment,and eventually,via four-component condensation reactions with cyano transition metal complexes.Here,we describe an unprecedented synthetic approach for the formation of unsymmetrically N-substituted Arduengo's carbenes and analogous N,O-heterocyclic carbenes that consists of the addition of propargylamine and propargylic alcohol,respectively,to coordinated isocyanide ligands.