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.