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

Multipalladium clusters possess peculiar structures and synergistic effects for reactivity and selectivity. Herein, -symmetric tripalladium clusters (, 0.5 mol %) afford C-regioselective SMCC of 2,4-dibromopyridine with phenylboronic acids or pinacol esters (C:C up to 98:1), in contrast to Pd(OAc) in ligand-free conditions. In addition, similar C-selectivity was achieved in Sonogashira, Negishi, and Kumada coupling reactions. This method highlights their powerful catalytic ability, exclusive C-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.