Advanced fine-tuning of grubbs/hoveyda olefin metathesis catalysts: a further step toward an optimum balance between antinomic properties.

A 95% yield in the cross metathesis of acrylonitrile with a model olefin is achieved at 25 degrees C with only 3 mol % of the new air-stable ruthenium catalyst 1f shown in the enclosed structural diagram. Even more remarkable are the performances of its boosted version 1g incorporating an electron-withdrawing group. Both these new enhanced versions of Hoveyda catalyst are readily available from Grubbs second generation precatalyst upon reaction with a styrenyl ether the end group of which has been functionalized by an ester function.

Ortho- and para-substituted Hoveyda-Grubbs carbenes. An improved synthesis of highly efficient metathesis initiators.

A novel highly efficient and general route to various 3- and 5-substituted 2-alkoxystyrenes, required for the preparation of Hoveyda-Grubbs catalysts, is described.