Phase Tags in the Recycling of Homogeneous Grubbs Catalysts

Since they were first synthesized in 1992, the ruthenium catalyst named after Nobel Laureate R. H. Grubbs have become a useful tool in organic synthesis. Compared to conventional heterogeneous metathesis catalysts, Grubbs catalysts are more reactive, faster to initiate and better for reaction control. Grubbs catalysts have been employed in good effort both in academia and industry, the later in the synthesis of certain pharmaceutical intermediates. 2 One variety of Grubbs catalyst, known as second generation Hoveyda-Grubbs Catalyst, contain N-heterocyclic carbene (NHC) ligands and chelating benzylidene ligands (Fig. 1). These second generation catalysts exhibit enhanced stability and reactivity.