The Clicked Pyridyl‐Triazole Ligand: From Homogeneous to Robust, Recyclable Heterogeneous Mono‐ and Polymetallic Palladium Catalysts for Efficient Suzuki–Miyaura, Sonogashira, and Heck Reactions
Various mono‐ and polymetallic palladium complexes containing a 2‐pyridyl‐1,2,3‐triazole (pyta) ligand or a nonabranch‐derived (nonapyta) ligand have been synthesized by reaction of palladium acetate with these ligands according to a 1:1 metal‐ligand stoichiometry and used as catalysts for carbon‐carbon cross‐coupling including the Suzuki–Miyaura, Sonogashira and Heck reactions. The unsubstituted monopalladium and nonapalladium complexes were insoluble in all the reaction media, whereas tri‐ and tetranuclar palladium complexes were soluble, which allowed conducting catalysis under either homogeneous or heterogeneous conditions. The organopalladium complexes were characterized by standard analytical and spectroscopic methods and by thermogravimetry showing decomposition above 110 °C. Both types of catalysts showed excellent activity for these cross carbon‐carbon bond formations involving aryl halides including activated aryl chlorides or acyl chloride. Besides the comparison between homogeneous and heterogeneous catalysis, the key feature of these catalysts is their remarkable robustness that allowed recycling at least ten times in the example of the Heck reaction with excellent yields and without significant reduction of the conversion.
Document Type: Research Article
Affiliations: 1: ISM, UMR CNRS N° 5255, Univ. Bordeaux, 351 Cours de la Libération, 33405 Talence Cedex, France, Fax: (+33)-5-4000-6994 2: ICMCB-CNRS, UPR9048, 87, Avenue du Docteur Schweitzer, 33608 Pessac Cedex, France
Publication date: January 14, 2013