N-heterocyclic Carbene-palladium(?)-1-methylimid Azole Complex Catalyzed C-H Bond Arylation

In this paper, the direct C-H bond arylation of imidazo[1,2-a]pyridines and benzoxazoles catalyzed by an N-heterocylic carbene-palladium(II)-1-methylimidazole [NHC-Pd(II)-Im] complex is introduced, which can be divided into the following two parts:1) NHC-Pd(?)-Im complex catalyzed direct C-H bond arylation of imidazo[1,2-a]pyridines with aryl chlorides was introduced in the first part. Under the suitable conditions, all reactions between various imidazo[1,2-a]pyridines and aryl chlorides worked well to give the desired C3-H arylated products in acceptable to high yields, giving a convenient and alternative method for the direct C-H bond arylation of imidazo[1,2-a]pyridines, using the economic and easily available aryl chlorides as the arylating reagents.2) NHC-Pd(II)-Im complex catalyzed direct C-H bond arylation of benzoxazoles with p-toluenesulfonates was introduced in the second part.Under the suitable conditions, all reactions between various benzoxazoles and p-toluenesulfonates worked well to give the desired C2-H arylated products. This method gave a broader space for the application of N-heterocyclic carbene-palladium complexes in organic synthesis.