Improved ruthenium catalysts for Z-selective olefin metathesis.

Benjamin K Keitz, Koji Endo, Paresma R Patel, Myles B Herbert, Robert H Grubbs

Index: J. Am. Chem. Soc. 1st ed., 134 , 693-699, (2012)

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Abstract

Several new C-H-activated ruthenium catalysts for Z-selective olefin metathesis have been synthesized. Both the carboxylate ligand and the aryl group of the N-heterocyclic carbene have been altered and the resulting catalysts evaluated using a range of metathesis reactions. Substitution of bidentate with monodentate X-type ligands led to a severe attenuation of metathesis activity and selectivity, while minor differences were observed between bidentate ligands within the same family (e.g., carboxylates). The use of nitrato-type ligands in place of carboxylates afforded a significant improvement in metathesis activity and selectivity. With these catalysts, turnover numbers approaching 1000 were possible for a variety of cross-metathesis reactions, including the synthesis of industrially relevant products.© 2011 American Chemical Society