An ionic liquid-supported ruthenium carbene complex: a robust and recyclable catalyst for ring-closing olefin metathesis in ionic liquids.

The synthesis of an ionic liquid-supported olefin metathesis catalyst derived from Grubb's ruthenium carbene complex is described. This new supported catalyst has been used in BMI.PF6 solvent, and this allowed success in solving the challenging problem of catalyst recycling. The IL catalyst in BMI.PF6 can be recovered and reused up to 10 consecutive cycles in RCM reactions of several dienes with excellent conversions. Moreover, the IL catalyst shows a remarkable stability in BMI.PF6 and can be stored several months without loss of activity. These results clearly demonstrate the importance of anchoring an imidazolium ionic liquid pattern to the catalyst to avoid its leaching from the BMI.PF6 phase.