Application of transition metal nanoparticles as catalysts for organic transformations has been attracting wide interest as nanoparticle-based catalytic systems might exhibit superior catalytic activities than the corresponding bulk materials. However, the main difficulty is that such small particles are almost impossible to separate by conventional means, which can lead to the blocking of filters and valves by the nanoparticle catalyst. We have conveniently prepared ultra small palladium(0) particles (less than 1 nm) on magnetic nanoparticle supports, in which immobilized auxiliaries are used as stabilizing ligands. These catalysts were active for Suzuki crosscoupling and Heck reactions giving isolated yields of 83 % and 56 %, respectively. In addition, the catalyst can be easily separated using a magnet and reused several times with sustained activity.

The Hoveyda-Grubbs catalyst has been successfully immobilized on surface-modified magnetic nanoparticles with a loading amount of 0.28 mmol ruthenium/g (magnetic support). The supported catalysts were active for the self-metathesis of methyl oleate and macro-monomer in a quantitative conversion, respectively. In addition, the catalyst can be easily separated by using a magnet and reused several times with sustained activity.