A PS-DES immobilized ruthenium carbene: a robust and easily recyclable catalyst for olefin metathesis
摘要:
The butyldietliylsilyl polystyrene (PS-DES) supported ruthenium carbene 7 is a robust, practical and easily recyclable catalyst for olefin metathesis of substituted olefins. (C) 2002 Published by Elsevier Science Ltd.
The design, synthesis, stability, and catalytic activity of nitro-substituted Hoveyda-Grubbs metathesis catalysts are described. The highly active and stable meta- and para-substituted complexes are attractive from a practical point of view. These catalysts operate in very mild conditions and can be successfully applied in various types of metathesis [ring-closing metathesis, cross-metathesis (CM), and enyne metathesis]. Although the presence of a NO2 group leads to catalysts that are dramatically more active than both the second-generation Grubbs's catalyst and the phosphine-free Hoveyda's carbene, enhancement of reactivity is somewhat lower than that observed for a sterically activated Hoveyda-Grubbs catalyst. Attempts to combine two modes of activation, steric and electronic, result in severely decreasing a catalyst's stability. The present findings illustrate that different Ru catalysts turned out to be optimal for different applications. Whereas phosphine-free carbenes are catalysts of choice for CM of various electron-deficient substrates, they exhibit lower reactivity in the formation of tetrasubstituted double bonds. This demonstrates that no single catalyst outperforms all others in all possible applications.
A Highly Efficient Ruthenium Catalyst for Metathesis Reactions
A PS-DES immobilized ruthenium carbene: a robust and easily recyclable catalyst for olefin metathesis
作者:Karol Grela、Mariusz Tryznowski、Michał Bieniek
DOI:10.1016/s0040-4039(02)02283-9
日期:2002.12
The butyldietliylsilyl polystyrene (PS-DES) supported ruthenium carbene 7 is a robust, practical and easily recyclable catalyst for olefin metathesis of substituted olefins. (C) 2002 Published by Elsevier Science Ltd.