Impact of NHC ligand conformation and solvent concentration on the ruthenium-catalyzed ring-closing metathesis reaction.

Michele Gatti, Ludovic Vieille-Petit, Xinjun Luan, Ronaldo Mariz, Emma Drinkel, Anthony Linden, Reto Dorta

Index: J. Am. Chem. Soc. 131 , 9498, (2009)

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Abstract

Two saturated N-heterocyclic carbene ligands with substituted naphthyl side chains were used for the preparation of Blechert-type ruthenium metathesis precatalysts. The resulting conformers of the complexes were separated and unambiguously assigned by X-ray diffraction studies. All new complexes were compared in terms of activity to the original, SIMes-derived Blechert catalyst and were shown to be superior. A study on the impact of solvent concentration in RCM reactions using the most active of these new catalysts ultimately led to the ring closing of a variety of substrates at very low catalyst loadings.