Metathesis of functionalized olefins

Abstract

The metathesis of olefins bearing functional groups provides potential routes to many valuable compounds. Most methathesis catalysts, however, are easily poisoned by polar compounds; so far, only a few catalyst systems have proven to be active in metathesizing functionalized olefins. In the homogeneous metathesis of these substrates the catalyst system WCl 6-(CH 3) 4Sn is still the best known. In addition to its well-known application in the conversion of unsaturated oxygen-containing olefins, such as (fatty) acid esters and unsaturated ethers, its effectiveness for the homogeneous metathesis of unsaturated nitriles has recently been proven. The first example of a catalyst for the heterogeneous metathesis of functionalized olefins is Re 2O 7/Al 2O 3, promoted by a small amount of an alkyltin compound. The system Re 2O 7/Al 2O 3-(CH 3) 4Sn is active — and very selective — in the metathesis of unsaturated acid esters and other hetero-atom containing olefins, even in situations where homogeneous systems fail. To be of interest for the chemical industry it is, however, necessary to develop catalysts which are more active and more stable than the catalysts known at the moment.