C–H Arylation of Imidazo[1,2-a]pyridines and Zolimidines Catalyzed by Synergistic Tripalladium Clusters

Tripalladium cluster [Pd 3 ] + -1-3 (0.33 mol %) presented superior reactivity in the C-H arylation of imidazo[1,2-a]pyridines and zolimidines with aryl halides compared to palladium monomers and nanoparticles, affording important imidazole[1,2-a]pyridine and zolimidine derivatives that featured excellent fluorescent and pharmaceutical properties. This method highlights the low catalyst usage, mild conditions, scale-up practicality, and broad substrate scope. Mechanistic and kinetic analyses indicated that [Pd3]+ most likely remained intact throughout this synergistic catalytic process.