Grubbs' Catalyst - Second Generation Catalyst

Second Generation Catalyst

The second generation catalyst has the same uses in organic synthesis as the first generation catalyst, but generally with higher activity. This catalyst is stable toward moisture and air, thus is easier to handle in the lab.

Shortly before the discovery of the 2nd generation Grubbs' catalyst, a very similar catalyst based on an unsaturated N-heterocyclic carbene (1,3-bis(2,4,6-trimethylphenyl)imidazole) was reported independently by Nolan and Grubbs in March 1999, and by Fürstner in June of the same year. Shortly thereafter, in August 1999, Grubbs reported the 2nd generation catalyst, based on a saturated N-heterocyclic carbene (1,3-bis(2,4,6-trimethylphenyl)dihydroimidazole):

In both the saturated and unsaturated cases a phosphine ligand is replaced with an N-heterocyclic carbene (NHC), which is characteristic of all 2nd generation type catalysts.

Both the 1st and 2nd generation catalysts are commercially available, along with many derivatives of the 2nd generation catalyst.