Reactivation of a Ruthenium-Based Olefin Metathesis Catalyst

First-generation Hoveyda–Grubbs olefin metathesis
catalyst was purposely decomposed in the presence of ethylene, yielding
inorganic species that are inactive in the ring-closing metathesis
(RCM) of the benchmark substrate diethyl diallylmalonate (DEDAM).
The decomposed catalyst was treated with 1-(3,5-diisopropoxyphenyl)-1-phenylprop-2-yn-1-ol
(3) to generate an olefin metathesis active ruthenium
indenylidene-ether complex in 43% yield. This complex was also prepared
independently by reacting RuCl2(p-cymene)­(PCy3) with the organic precursor 3. The activity
of the isolated reactivated catalyst in the RCM of DEDAM is similar
to that of the independently prepared complex.