Improvement in olefin metathesis using a new generation of ruthenium catalyst bearing an imidazolylidene ligand: Synthesis of heterocycles

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A number of heterocycles have been prepared in very good yields using 1,3-dimesitylimidazol-2-ylidene ruthenium benzylidene 1. This catalyst displays increased activity for ring closing metathesis of some hindered heterodienes which did not cyclize using the Grubbs catalyst 2. The scope of the olefin metathesis has been expanded.