Regioselective Suzuki–Miyarua Cross-Coupling for Substituted 2,4-Dibromopyridines Catalyzed by C3-Symmetric Tripalladium Clusters

Multipalladium clusters possess peculiar structures and synergistic effects for reactivity and selectivity. Herein, C₃-symmetric tripalladium clusters (1, 0.5 mol %) afford C₂-regioselective SMCC of 2,4-dibromopyridine with phenylboronic acids or pinacol esters (C₂:C₄ up to 98:1), in contrast to Pd(OAc)₂ in ligand-free conditions. In addition, similar C₂-selectivity was achieved in Sonogashira, Negishi, and Kumada coupling reactions. This method highlights their powerful catalytic ability, exclusive C₂-selectivity, broad substrate scope, efficient amplification, and multiple ligand-exchange feasibility and demonstrates that the conventional sites could be successfully regulated or even reversed by catalysts.