초록 |
Recently, complexes of N-heterocyclic carbenes (NHCs) have drawninterest, due to their ease of synthesis, high stability and excellent catalytic properties toward a variety of reactions. Silica-supported catalysts derived from palladium complexes of mono-/bi-dentate NHC ligands were easily prepared and characterized. Any compositions of mono- and bi-dentate NHC-Pd complexes exhibit higher activity in Suzuki reaction between arylhalides and arylboronic acids under mild condition. However, it was found that leaching amounts of the catalytic species into solution from the support were different from one composition to another. From this result, we found that bi-dentate Pd complexes afforded an increased stability, and provided a clear improvement in the recovery and reuse for the supported catalysts. |