Oxime carbapalladacycle covalently anchored to high surface area inorganic supports or polymers as heterogeneous green catalysts for the Suzuki reaction in water

An oxime carbapalladacycle known as an extremely active homogeneous catalyst for the Suzuki coupling in water has been conveniently modified and anchored on high surface area SiO2, MCM-41, and polystyrene-divinylbenzene and ethylenglycol dimethylacrylate polymers. The resulting solids were characterized by analytical and spectroscopic (UV-vis and IR) techniques and tested as catalysts for the reaction of 4-chloroacetophenone with phenylboronic acid in water, dioxane, and a mixture of both. Differences in activity depending on the support were remarkable, the palladium complex being more active for the reactions in water when supported on SiO2 or MCM-41. The catalysts were truly heterogeneous (no leached palladium) and when anchored on SiO2 were reused seven times without loosing activity. Palladium complex anchored in SiO2 was also tested as Suzuki catalyst for a wide range of bromo-, chloro-, and even fluoroaromatics.