Palladium(0) deposited on PAMAM dendrimers as a catalyst for C-C cross coupling reactions.

PAMAM dendrimers of generations G2-G3 as well as a partially substituted derivative of generation G4 and a low-molecular-weight tricyclic ligand 4 were used to bind Pd(0) nanoparticles. The obtained adducts were tested as catalysts for C-C cross-coupling reactions, such as the Suzuki-Miyaura, Hiyama, Heck and Sonogashira reaction. The highest yields of the coupling product, diphenylacetylene, were obtained with all the catalysts studied in the Sonogashira coupling performed in ethanol with K₂CO₃ as base. Very good results, 85-100%, were also found in the Suzuki-Miyaura cross-coupling, while the efficiency of the Hiyama coupling appeared lower, with 38-52% of 2-methylbiphenyl formed. In all reactions, the G2-Pd(0) catalyst, containing an unmodified dendrimer, afforded the highest yields of the cross-coupling products.