Hybrid silica materials derived from Hoveyda–Grubbs ruthenium carbenes. Electronic effects of the nitro group on the activity and recyclability as diene and enyne metathesis catalysts
- 作者：Xavier Elias ; Roser Pleixats ; Michel Wong Chi Man
- 关键词：Catalyst immobilization ; Metathesis ; Organic– ; inorganic hybrid materials ; Ruthenium ; Sol– ; gel process
- 刊名：Tetrahedron
- 出版年：2008
- 期刊代码：107_00404020
- 类别：ch
- 出版时间：7 July 2008
- 卷：64
- 期：28
- 页码：6770-6781
- 文件大小：530 K
摘要
The preparation of several organic–inorganic hybrid materials by sol–gel process derived from Hoveyda-type monomers is described. One of them presents a nitro group at the para position with respect to the alkoxy moiety. These materials were treated with Grubbs catalysts to generate the corresponding Hoveyda–Grubbs carbene ruthenium complexes covalently bonded to the silica matrix, which were tested as recyclable catalysts for diene and enyne RCM. Electronic effects of the nitro group resulted in enhanced activity of the catalyst. Whereas the recyclability decreased in RCM of dienes, the presence of this electron-withdrawing group was highly advantageous for the RCM of enynes, the reusability being greatly improved.