Metathesis reactions: Effect of additives as co-catalysts to Grubbs' or Schrock's catalyst

Olefin metathesis catalysts by Schrock and Grubbs have witnessed tremendous success as it has led to the development of several metathesis transformations. However, the use of additives in olefin metathesis reactions which employs the commercially available Schrock's or Grubbs's catalyst has been investigated. It has resulted in better catalyst performance, catalyst stability, suppression of other non-metathetic reactions like olefin isomerization, self-metathesis and improved desired metathesis product yield. This survey will firstly highlight some types of metathesis reactions, followed by a brief overview of the Schrock's and Grubbs's catalysts and then enumerate the influence of additives as co-catalyst on the activity and selectivity of the specified available olefin metathesis catalyst.