Coupling Reactions Of Aryl Catalyzed By Palladium Supported On Metal-organic Frameworks

Biaryl groups is key skeleton of many natural and industrial chemical compounds; formation of the biaryls has been an essential part of modern organic syntheses and has played an important role in processes of pharmacies, pesticides and fine chemicals as well. Therefore, the research of aryl coupling reactions has both academic and practical significance. Suzuki-Miyaura reaction and Ullmann reaction are the most powerful and convenient methods for the construction of biaryls.In the work, palladium nanoparticle supported on a typical Metal-Organic Framework named MOF-5, was prepared and used as a catalyst for Suzuki-Miyaura reaction and Ullmann reaction. The microstructure and features of the synthesized catalyst was characterized by PXRD, SEM, TEM, and N2-adsorption respectively. With Pd/MOF-5 catalytic system, the effects of solvent, temperature of reaction, choice of base, and the amount of catalyst, have also been investigated for the optimization of Suzuki-Miyaura cross-coupling. And accordingly, the catalyst system is applied to various different substrates, and the reuse of the catalyst was investigated as well.The results showed that the Suzuki-Miyaura cross-coupling reaction could be high-efficiently catalyzed by Pd/MOF-5 in presence of NaOH or KOH in ethanol or methanol at room temperature. The catalyst is on low-demand, easy separated, and good performed within 5 reuse cycles. Furthermore, the Ullmann reaction catalyzed by Pd/MOF-5 was also investigated. The bromoarenes gave the mild yields, thus it will be further investigated in the future.