In our search for more-selective olefin metathesiscatalysts, a series of Hoveyda–Grubbs-type second-generation complexes bearing unsymmetrical N-heterocycliccarbene (NHC) ligands were synthesized and tested in model reactions. It was found that the N-benzyl substituent in NHC has a positive influence on the selectivity of the newly obtained catalysts in the self-metathesis reaction of α-olefins.
set of olefinmetathesis catalysts bearing a ruthenium amide moiety was synthesised. In the ruthenium amide form these complexes exhibit very low activity in standard metathesis reactions. However, a dramatic increase of activity was observed upon in situ activation with trimethylsilyl chloride or HCl, allowing successful application of such catalysts in a number of model ring‐closing metathesis, cross‐metathesis
Efficient, durable and reusable olefin metathesis catalysts with high affinity to silica gel
作者:Krzysztof Skowerski、Piotr Kasprzycki、Michał Bieniek、Tomasz K. Olszewski
DOI:10.1016/j.tet.2013.06.056
日期:2013.9
The new Scorpio type olefin metathesis catalysts with very high affinity to silica gel are reported. After completion of the reaction, those complexes can be efficiently separated from reaction product by direct filtration of reaction mixture through a short pad of silica gel. Products obtained by this methodology are contaminated with low amounts of residual ruthenium. Especially, catalyst (H2IPr)(Cl)(2)Ru=C(H)(C6H4OR) (5b, R=CH(Me)(C(O)N(Me)OMe) exhibited very high activity and could be easily recovered and reused. Additionally, this catalyst was found to be effective already at 0.1-0.5 mol % and showed good compatibility with environmentally benign solvents. (C) 2013 Elsevier Ltd. All rights reserved.