A convenient method to remove ruthenium byproducts from olefin metathesis reactions using polymer-bound triphenylphosphine oxide (TPPO)

Ruthenium byproducts from ring-closing metathesis reactions can be removed by refluxing the crude reaction mixture with resin-bound triphenylphosphine oxide (TPPO) in toluene or by stirring with dimethyl sulfoxide (DMSO) and silica gel at room temperature. Residual levels of ruthenium can be achieved that are as low as 0.04 mu g per 5 mg of product when a combination of TPPO, DMSO, and silica gel is used. The polymer-bound TPPO retained its efficiency after being recycled six times.