Synergistic Palladium/Silver/Ligand Catalysis for C−H Alkenylation of 2,1,3-Benzofused Heterodiazoles

Abstract

The combination of palladium and silver complexes has emerged as a bimetallic catalytic system in C−H activation, frequently outperforming palladium-only systems. Beyond the conventional roles of silver (I) salts serving as oxidants, halide scavengers, and Lewis acids, Pd−Ag bimetallic synergism has been shown to facilitate C−H cleavage. In this study, we explore the incorporation of a pyrazolopyridone (PzPyOH) ligand into a Pd−Ag bimetallic catalytic system, which together promote both C−H cleavage and migratory insertion processes. This synergistic approach enables dehydrogenative C−H alkenylations at the C4 position of 2,1,3-benzothiadiazole, 2,1,3-benzoxadiazole, and 2,1,3-benzotriazole with alkenes. These results demonstrate the potential of combining novel ligands with heterobimetallic systems to facilitate other elementary steps beyond C−H cleavage, suggesting their broader applicability in C−H functionalization.