Palladium nanoparticles supported on modified polystyrene resin as a polymeric catalyst for Sonogashira-Hagihara coupling reactions

摘要

Pd(0) nanoparticles supported on modified crosslinked polystyrene were synthesized and characterized. Crosslinked polystyrene was reacted with trioxane and chlorotrimethylsilane in the presence of SnCl$_{4}$ to form Merrifield resin. The Merrifield resin was then converted to polymer-bound $eta $-aminoalcohol and subsequently to $eta$-aminophosphinite ligand. This polymeric ligand was reacted with PdCl$_{2}$ to obtain a polymeric Pd(0) complex. The TEM image of the Pd catalyst showed good dispersion of catalytic sites. The Pd catalyst exhibits excellent activity and stability in copper-free Sonogashira-Hagihara cross-coupling reactions under aerobic conditions. This protocol can be applied efficiently to the coupling reactions of chloro- as well as iodo- and bromo-arenes. The catalyst can be reused several times without any considerable decrease in its activity.