First-Generation Ruthenium Indenylidene Catalysts Bearing Two Phosphine Ligands

First-Generation Ruthenium Indenylidene Catalysts Bearing Two Phosphine Ligands 

Using alkylphosphines based on a phosphabicyclo [3.3.1] nonane motif, RuCl2(9-cyclohexyl-9-phosphabicyclononane)(3-phenylindenylidene) 19 and RuCl2(9-isobutyl-9-phosphabicyclononane)(3-phenylindenylidene) 20 were 

The iButylPhoban complex 20, which is commercially available, has been used to prepare a second-generation, ruthenium indenylidene catalyst [37]. 

The highly substituted, chelating, vinylcarbene ruthenium complex 22 has been prepared by Fiirstner [40] via the reaction of 6 with ortho-isopropoxyethynylbenzene in dichloromethane at room temperature. Silver chloride (AgCl) was added to this reaction as a phosphine scavenger. Complex 22, which results from a formal insertion of the triple bond into the Ru=C via a [2-1-2] cycloaddition, was not evaluated as a metathesis catalyst in this report. 

First-Generation Ruthenium indenylidene Catalysts Bearing a Chelating Ligand 

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