Organic-inorganic hybrid silica material derived from a monosilylated Grubbs-Hoveyda ruthenium carbene as a recyclable metathesis catalyst.
نویسندگان
چکیده
The synthesis of a monosilylated Grubbs-Hoveyda ruthenium alkylidene complex is described, as well as the preparation and characterization of the corresponding material by sol-gel cogelification with tetraethoxysilane (TEOS) and the assay of this recyclable supported catalyst in ring-closing diene and enyne metathesis reactions under thermal and microwave conditions.
منابع مشابه
Phase Tags in the Recycling of Homogeneous Grubbs Catalysts
Since they were first synthesized in 1992, the ruthenium catalyst named after Nobel Laureate R. H. Grubbs have become a useful tool in organic synthesis. Compared to conventional heterogeneous metathesis catalysts, Grubbs catalysts are more reactive, faster to initiate and better for reaction control. Grubbs catalysts have been employed in good effort both in academia and industry, the later in...
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Two triethoxysilyl-functionalized N-heterocyclic carbene ligands have been synthesized and used to prepare the corresponding second-generation ruthenium olefin metathesis catalysts. These complexes were then grafted onto silica gel, and the resulting materials were efficient heterogeneous catalysts for a number of metathesis reactions. The solid-supported catalysts were shown to be recyclable o...
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for olefin metathesis have been reported, for which strikingly different influences of the ligands on the efficiency of C C bond formation have been observed. For example, notable effects have been found in the class of alkoxy benzylidene ligands first introduced by Hoveyda and coworkers. Phosphine-free complexes such as the secondgeneration Hoveyda–Grubbs catalyst (4 ; IMesH2= 1,3-dimesityl-4,...
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Density function theory calculations reveal that the Grubbs-Hoveyda olefin metathesis pre-catalyst is activated by the formation of a complex in which the incoming alkene substrate and outgoing alkoxy ligand are both clearly associated with the ruthenium centre. The computed energies for reaction are in good agreement with the experimental values, reported here.
متن کاملIncreased efficiency in cross-metathesis reactions of sterically hindered olefins.
Efficiency in olefin cross-metathesis reactions is affected upon reducing the steric bulk of N-heterocyclic carbene ligands of ruthenium-based catalysts. For the formation of disubstituted olefins containing one or more allylic substituents, the catalyst bearing N-tolyl groups is more efficient than the corresponding N-mesityl catalyst. In contrast, the formation of trisubstituted olefins is mo...
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ورودعنوان ژورنال:
- Molecules
دوره 15 8 شماره
صفحات -
تاریخ انتشار 2010