Imidazole olefin metathesis

Imidazole-containing reagents have found useful applications in a variety of organic transformations. A second generation of ruthenium-based olefin metathesis catalysts... 

Ruthenium(n) systems containing imidazol-2-ylidene or imidazolidin-2-ylidene have been used to catalyze the synthesis of 2,3-dimethylfuran starting at (Z)-3-methylpent-2-en-4-yn-l-ol [Eq. (54)]. The activity of the catalyst strongly depends on the nature of the NHC ligand. Benzimidazolin-2-ylidenes give the best results for this transformation. Similar systems have also been used for olefin metathesis reactions. ... 

Ruthenium alkylidene compounds bearing two imidazol-2-ylidene ligands (6) have also been prepared and, in olefin metathesis, they exhibit a catalytic activity comparable to that of the... 

To further expand the scope of Ru-arene catalyst precursors in olefin metathesis, we have investigated the replacement of phosphine ligands by NHC species, either preformed or generated in situ, in monometallic dichlororuthenium complexes of the [RuCl2(p-cymene)(L)] type/ In this contribution, we summarize the main results that were obtained with both imidazole- or triazole-based ancillary ligands for the ROMP of cyclooctene. 

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