Synthesis of Pyrimidine-Modified NHC Ruthenium-Alkylidene Catalysts and Their Application in RCM, CM, EM and ROMP Reactions



A new type of N-heterocyclic carbene bearing ruthenium olefin metathesis catalyst was prepared through the incorporation of a chelated pyrimidinyl methylene subunit, in which electron-rich substituents were attached to stabilize the ruthenium complexes. These catalysts were successfully used in various types of olefin metathesis reactions, including ring-closing metathesis (RCM), cross-metathesis (CM), enyne metathesis (EM), and ring-opening metathesis polymerization (ROMP) reactions. The results therein showed that the presence of an electron-deficient pyrimidine structure greatly enhanced the new NHC ruthenium complexes' catalytic activities.