Ruthenium Catalysts Supported by Amino‐Substituted N‐Heterocyclic Carbene Ligands for Olefin Metathesis of Challenging Substrates

• Published in: Chemistry : a European journal 2017-02, Vol.23 (8), p.1950-1955
• Main Authors: César, Vincent, Zhang, Yin, Kośnik, Wioletta, Zieliński, Adam, Rajkiewicz, Adam A., Ruamps, Mirko, Bastin, Stéphanie, Lugan, Noël, Lavigne, Guy, Grela, Karol
• Format: Article
• Language: English
• Subjects: Carbenes; Catalysis; Catalysts; Chemical Sciences; Chemistry; Coordination chemistry; C−C bond formation; Decomposition reactions; heterocycles; homogeneous catalysis; Ligands; Metathesis; Olefins; Ruthenium
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201604934

N‐Heterocyclic carbene (NHC) ligands IMesNMe2 and IMes(NMe2)2 derived from the well‐known IMes ligand by substituting the carbenic heterocycle with one and two dimethylamino groups, respectively, were employed for the synthesis of second‐generation Grubbs‐ and Grubbs–Hoveyda‐type ruthenium metathesis precatalysts. Whereas the stability of the complexes was found to depend on the degree of dimethylamino‐substitution and on the type of complex, the backbone‐substitution was shown to have a positive impact on their catalytic activity in ring‐closing metathesis, with a more pronounced effect in the second‐generation Grubbs‐type series. The new complexes were successfully implemented in a number of challenging olefin metathesis reactions leading to the formation of tetra‐substituted C=C double bonds and/or functionalized compounds. A strong backbone: The introduction of N‐heterocyclic carbene ligands that incorporate dimethylamino groups as heterocyclic substituents leads to an increased activity in second‐generation ruthenium metathesis catalysts (see figure).