text: Schrock entered the olefin metathesis field in 1979 as an extension of work on tantalum alkylidenes. The initial result was disappointing as reaction of  with ethylene yielded only a metallacyclopentane, not metathesis products:
  But by tweaking this structure to a  (replacing chloride by t-butoxide and a cyclopentadienyl by an organophosphine, metathesis was established with cis-2-pentene. In another development, certain tungsten oxo complexes of the type  were also found to be effective.
  Schrock alkylidenes for olefin metathesis of the type  were commercialized starting in 1990.
  The first asymmetric catalyst followed in 1993
  With a Schrock catalyst modified with a BINOL ligand in a norbornadiene ROMP leading to highly stereoregular cis, isotactic polymer.