p(HEMA)-Pd(II) and p(HEMA-MAH)-Pd(II) Microspheres: Efficient, Recyclable and Ligand-Free Catalyst for Suzuki-Miyaura Cross-Coupling Reaction in Water

In this study, the authors report the synthesis and characterization of new poly(hydroxyethyl methacrylate) palladium(II) (p (HEMA)-Pd(II)) and poly(hydroxyethyl methacrylate-N-methacryloyl-(L)-histidine methyl ester) palladium(II), p(HEMA-MAH)Pd(II) microsphere catalysts, and their catalysis in Suzuki-Miyaura coupling reactions of aryl bromides with phenylboronic acid in water. The microsphere catalysts were characterized by SEM, ICP-MS, FTIR, and diffuse-reflactance UV-visible spectroscopy. The p(HEMA)-Pd(II) and p(HEMA-MAH)-Pd(II) microsphere catalysts were active catalysts in Suzuki-Miyaura coupling reactions of arylbromides with phenylboronic acid affording biphenyls in high yield. Recycling experiments showed that the p(HEMA)-Pd(II) and p(HEMA-MAH)-Pd(II) microsphere catalysts could be used seven or ten times with essentially no loss in activity in the Suzuki-Miyaura coupling reactions.