A simple method for preparing imidazolium-based polymer as solid catalyst for Suzuki-Miyaura reaction

Polymers containing the structure of N-heterocyclic carbenes (NHCs) have attracted much interest due to their superior complexing ability to metal ions and good recyclability, which make them promising candidates as solid supporters. Herein, we developed an easy method to synthesize polyimidazolium chloride salt (PImCl) via one-step method in mild conditions. After PImCl was chelated with palladium chloride in 3-chloropyridine, this NHC-Pd polymer was employed as the solid catalyst for Suzuki reactions of aryl bromides and phenylboronic acid. The catalytic activity of the NHC-Pd polymer was high for many different substrates. Moreover, the Suzuki reaction of 4-bromoanisole with phenylboronic acid could be catalyzed by this NHC-Pd polymer in mild conditions. Furthermore, this solid catalyst could be easily isolated by centrifugal separation. After several recycling runs, the catalytic activity decreased little. Compared with the conventional methods, this method was much simpler and more efficient, which showed enormous potential in preparing new heterogeneous supporter of porous polyimidazolium chloride salt.