Prepatation, Characterization Of Supported Palladium Catalysts And Its Application In C-C/C-N Coupling Reaction

Heterocyclic compound,with pyrimidine scaffolds,is one of the important pharmaceutical intermediate,and plays a central part in the synthesis of drugs by its higher biological activity.In coupling reaction process,it is easy to obtained pyrimidine compounds by C-C/C-N bond formation.The biological activity and medicinal value of pyrimidine derivates could be improve with different substituents.However,most of the coupling reaction with heterocyclic compound was catalyzed by transition metal homogeneous catalysts,they suffer from a number of drawbacks for environmental,such as difficulties to purify and reuse after chemical reactions.From an environmental and economic viewpoint to solve the problem,the development of new heterogeneous catalyst system is attracted.Basing on green chemistry,a series of heterogeneous palladium catalyst,supported on natural biomacromolecule wool,palygorskite and graphene oxide,were prepared respectively.The support is cheap,non-toxicity and easy handle.And the catalyst was found to be an effective catalyst for the C–C/C–N coupling reaction of functionalized 3,4-dihydropyrimidin-2（1H）-ones:（1）A well-defined heterogeneous palladium catalyst,supported on natural wool fibre,was prepared via simple method.The catalyst was characterized by IR,XRD,SEM,ICP,XPS and etc.The structure and anchored mechanism of Wool-Pd（OAc）₂were explored.In our research,Wool-Pd（OAc）₂ was used as catalyst for the C-C/C-N coupling reaction of functionalized 3,4-dihydropyrimidin-2（1H）-ones,displayed great efficiency on the broaden scope of substrate under mild reaction conditions.In these reactions,Wool-Pd（OAc）₂ is stable,efficient and negligible metal leaching.It also retains good activity for at least ten successive runs without the aggregation and agglomeration of Pd particles.（2）We have successfully prepared graphene oxide（GO）supported PdCl₂ catalyst（GO-PdCl₂）,and GO was obtained according to the improved Hummer’s method.The catalysts have been applied in the C–C/C–N coupling reaction of pyrimidin-2-yl sulfonates with wide functional group tolerance.The results showed that GO-PdCl₂was high activity and can be reused for at least five successive runs.（3）Based on peculiarly resources of Gansu province,palygorskite supported palladium catalyst（PGS-APTES-Pd（OAc）₂）has been successfully prepared in water.It could be applied in aqueous-mediated Suzuki coupling reaction of aryl halides without assistance of any phosphine ligands.In the same way,PGS-APTES-Pd was used as catalyst for C-C/C-N coupling of pyrimidin-2-yl sulfonates.The catalysts were stable and retain good activity for reuse,and performed an endurable activity as well as the wide tolerance of the substrates.