Fast-Initiating, Ruthenium-based Catalysts for Improved Activity in Highly E-Selective Cross Metathesis.
Title | Fast-Initiating, Ruthenium-based Catalysts for Improved Activity in Highly E-Selective Cross Metathesis. |
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Authors | Ahmed, T.S.; Grubbs, R.H. |
Journal | J Am Chem Soc |
DOI | 10.1021/jacs.6b11330 |
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, (1)H 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). |