How Important Is the Release–Return Mechanism in Olefin Metathesis?

Abstract

From whose bourns no traveller returns, puzzles the will: UV/Vis, 19F NMR, and fluorescence spectroscopic studies (see graphic) provide no evidence supporting the boomerang mechanism in Grubbs–Hoveyda complexes, which is the return of the isopropoxy styrene as a benzylidene ether ligand following its release during catalyst initiation.