Study on the Effect of the Ligand Structure in Palladium Organometallic Catalysts in the Suzuki–Miyaura Cross-Coupling Reaction

In this communication, we present the results obtained using a family of cyclometallated palladium compounds as catalysts for the Suzuki–Miyaura cross-coupling reaction between an aryl halide and phenylboronic acid. We have studied the structural factors that enhance the efficiency of the catalyst for this process through the synthesis of a library of analogous compounds containing thiosemicarbazone ligands with substituted rings and ferrocene diphosphine (dppf). We found that the best conversion rates are obtained with ligands bearing methoxy-disubstituted aromatic rings, and that the process performance is improved when R2 is a methyl group bound to the thioamidic nitrogen. These results lay the foundations for the design and development of novel and more efficient palladium catalysts based on thiosemicarbazones.