A green catalyst for green chemistry: Synthesis and application of an olefin metathesis catalyst bearing a quaternary ammonium group

The novel catalyst 8, bearing a polar quaternary ammonium group, is very stable and can be easily prepared from commercially available reagents. Catalyst 8 can be efficiently used for olefin metathesis not only in traditional but also in aqueous media. Various ring closing-, cross- and enyne-metathesis reactions were conducted in water–methanol mixtures in air. The electron withdrawing quaternary ammonium group not only activates the catalyst chemically, but at the same time allows its efficient separation after reaction. Application of 8 leads to organic products of high purity, which exhibit very low ruthenium contamination levels (12–68 ppm) after filtering through a pad of silica gel.