Asymmetric cyclic alkyl amino carbene (CAAC) ruthenium complexes as improved catalysts for ethenolysis

Abstract

Ethenolysis, the cross metathesis reaction of an internal olefin with ethylene to generate two terminal olefin products, has long been proposed as a method for the rapid prodn. of commodity, value-added products from inexpensive, readily-available seed oil derivs. For application to commodity chems., the TON should be at least 50,000. Prior to this report, such a catalyst system had yet to be developed. Herein, we disclose ruthenium complexes of cyclic alkyl amino carbene (CAAC) ligands bearing asym. ortho substitution on the N-aryl ring, as potentially viable catalyst systems for ethenolysis reactions on an industrial scale. In the ethenolysis of Me oleate, these catalyst systems exhibit TONs > 100,000 and >90% selectivity for terminal olefins, at a loading of 3 ppm. Mechanistic investigations probing this remarkable activity are ongoing, and will also be presented in detail.