Cyclic Alkyl Amino Ruthenium Complexes—Efficient Catalysts for Macrocyclization and Acrylonitrile Cross Metathesis

The active species generated from ruthenium complexes bearing N-heterocyclic carbene (NHC) ligands exhibit limited stability under certain conditions (high dilution, high temperature) and in the presence of nitrile functionality. As a consequence, industrial implementation of metathesis for the production of important materials such as macrocyclic musks and polyamide 11 is uneconomical. Over the past decade, hundreds of ruthenium complexes bearing NHC ligands have been obtained. However, to this date, they have brought rather limited improvements in efficiency. In this paper, we report on cyclic alkyl amino carbene (CAAC) ruthenium complexes that promote highly challenging macrocyclization and cross metathesis (CM) with acrylonitrile reactions at loadings as low as 10−20 ppm