Palladium-Catalyzed Selective C-H Activation: A Simple Method to Synthesize C-3 Site Arylated Quinoline Derivatives

A novel protocol for the synthesis of 3-arylated quinoline derivatives has been developed using silver carbonate (Ag2CO3) and dioxygen (O-2) as the oxidants. In this method, quinolines acting as the parent reagent react with arenes under palladium acetate [Pd(OAc)(2)] catalysis along with 1-adamantanecarboxylic acid (Adm). The combination of the 1-adamantanecarboxylic acid ligand and the palladium catalyst is found to be an essential factor for achieving high activity and selectivity, and allows a wide range of 3-arylquinoline derivatives to be obtained in high yields. Moreover, a relevant mechanism is proposed, revealing that un der the palladium(II) catalysis a migratory insertion to C-3-H of quinolines and insertion to the C-H of arenes are key steps in this reaction. Mild reaction conditions and high selectivity of the reactive site provide potential for promising applications in drug discovery and functional materials.