Novel Water-Soluble Palladium Catalysts:Design, Preparation And Their Application In Suzuki-Miyaura Cross-Coupling Reactions

Aimed to resolve problems of current palladium catalysts for aqueous Suzuki-Miyuara reaction, two novel palladium catalysts have been developed in this thesis and their catalytic activity have also been evaluated in Suzuki-Miyaura reactions in water.First, a N,N-bidentate ligand (Ln@β-CD) was synthesized via " click reaction " and then coordinated with Pd(OAc)2to give the desired catalyst PdLn@B-CD, which was further characterized by1H NMR,2D ROESY NMR, ICP-MS. Under optimized reaction conditions, PdLn@β-CD can smoothly catalyzed the coupling reaction between aryl bromides (iodines) and aryl boronic acids in water under reflux, with isolated yields up to98%. Specificly, the catalyst showed high turnover numbers (TONs) and turnover frequencies (TOFs) up to9.9×108and4.9×108h-1, respectively. The detailed reason for the excellent catalytic activity was further studied and it was proved that the β-CD-fragement not only enhanced the catalyst’s water-solubility but also increased the substrates’concentration in water by recognition capacity. Second, a tetracoordinated palladium catalyst Pd(L-pro)2was prepared by coordination between Pd(OAc)2and L-proline, which acted as a N,O-bidentate ligand. And the catalyst was characterized by1H NMR,13C NMR, FT-IR, HR-MS. The obtained palladium catalyst showed promising catalytic activity for Suzuki-Miyaura reaction between aryl bromides (iodines) and aryl boronic acids in water under reflux, with isolated yields up to98%. Meanwhile, the catalyst could be reused for at least6times with no significant loss in its activity.