Mechanistic Studies of Enantioselective N-aryl, N-alkyl NHC Ruthenium Metathesis Catalysts in Asymmetric Ring-Opening Cross-Metathesis

Olefin metathesis is used widely for the construction of carbon-carbon double bonds and has extensive applications in organic and polymer synthesis, as well as materials chemistry. A symmetric metathesis provides an attractive methodology for synthesizing enantiopure molecules, and significant efforts have been directed toward the development of enantioselective catalysts. A symmetric ring-opening cross-metathesis (AROCM)(Scheme 1) has been employed as the key step in several total syntheses, affording the desired product in excellent enantiomeric excess (ee). Applications of AROCM have also been pursued in the synthesis of biologically relevant molecules. Imparting chirality from the catalyst to the substrate is challenging, and has been the focus of catalyst design for this purpose.