title: Fast-Initiating, Ruthenium-based Catalysts for Improved Activity in Highly E-Selective Cross Metathesis.
abstract: Ruthenium-based olefin metathesis catalysts bearing dithiolate ligands have been recently employed to generate olefins with high E-selectivity (>99% E) but have been limited by low to moderate yields. In this report,1H NMR studies reveal that a major contributing factor to this low activity is the extremely low initiation rates of these catalysts with trans olefins. Introducing a 2-isopropoxy-3-phenylbenzylidene ligand in place of the conventional 2-isopropoxybenzylidene ligand resulted in catalysts that initiate rapidly under reaction conditions. As a result, reactions were completed in significantly less time and delivered higher yields than those in previous reports while maintaining high stereoselectivity (>99% E).
authors.affiliation: The Arnold and Mabel Beckman Laboratory of Chemical Synthesis, Division of Chemistry and Chemical Engineering. California Institute of Technology , Pasadena, California 91125, United States.
authors.forename: Tonia S
authors.initials: TS
authors.lastname: Ahmed
authors.affiliation: The Arnold and Mabel Beckman Laboratory of Chemical Synthesis, Division of Chemistry and Chemical Engineering. California Institute of Technology , Pasadena, California 91125, United States.
authors.forename: Robert H
authors.identifier: 0000-0002-0057-7817
authors.initials: RH
authors.lastname: Grubbs