An efficient method for removal of ruthenium byproducts from olefin metathesis reactions

[GRAPHICS] Sequential treatment of the ring-closing metathesis reaction products with silica gel, activated carbon (50 equiv wt relative to the crude products), and column chromatography on silica gel efficiently removed dark brown ruthenium byproducts from the reaction mixture. After this treatment, colorless compounds could be obtained with a ruthenium level of 0.06-0.53 mug per 5 mg of product.