Sonogashira Cross-Coupling of Aryl Ammonium Salts by Selective C–N Activation Catalyzed by Air- and Moisture-Stable, Highly Active [Pd(NHC)(3-CF3-An)Cl2] (An = Aniline) Precatalysts

Abstract

We report the Sonogashira cross-coupling of aryl ammonium salts catalyzed by air- and moisture-stable [Pd(NHC)(3-CF3-An)Cl2] (An = aniline). This highly active Pd(II)-NHC complex features broad scope and excellent C-N activation selectivity in the challenging alkynylative cross-coupling of aryl ammonium salts. Full structural characterization and computational studies demonstrate the effect of pyridine to aniline replacement as highly effective stabilizing ancillary ligand in well-defined Pd(II)-NHCs. Considering the high reactivity and the recent commercialization of [Pd(NHC)(3-CF3-An)Cl2] (Millipore Sigma, no. 915165), this catalyst represents an attractive approach to the activation of C-N bonds of broad synthetic interest.