A Versatile and Highly Z-Selective Olefin Metathesis Ruthenium Catalyst Based on a Readily Accessible N-Heterocyclic Carbene

A ruthenium catalyst for Z-selective olefin metathesis has been synthesized from a readily accessible N-heterocyclic carbene (NHC) ligand that is prepared using an efficient, practical, and scalable multicomponent synthesis. The desired ruthenium complex with cyclometalated NHC ligand is obtained by means of selective C(sp3)-H activation at the adamantyl fragment and X-ray diffraction analysis unambiguously confirmed the structure of the precatalyst. The catalyst demonstrated attractive catalytic performance in self- and cross-metathesis at low catalyst loading to afford the desired internal olefins with high conversion and very high Z-selectivity (up to >99%). The versatility of the chelated catalyst is illustrated by the high cis-selectivity (up to >98%) and high tacticity control (up to >98% syndiotactic) achieved in ring-opening polymerization, allowing for the production of highly microstructurally controlled norbornene-, norbornadiene-, and cyclopropene-derived polymers.