Polymer-Supported Bis(oxazolines) and Related Systems: Toward New Heterogeneous Enantioselective Catalysts
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- 作者：M. I. Burguete ; J. M. Fraile ; E. Garcí ; a-Verdugo ; S. V. Luis ; V. Martí ; nez-Merino ; and J. A. Mayoral
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2005
- 出版时间：November 9, 2005
- 年：2005
- 卷：44
- 期：23
- 页码：8580 - 8587
- 全文大小：415K
- 年卷期：v.44,no.23(November 9, 2005)
- ISSN：1520-5045
文摘
Polymer-supported bis(oxazoline) and related ligands have been prepared by grafting and bypolymerization methodologies under a variety of conditions. The corresponding Cu complexeshave been assayed as catalysts for the cyclopropanation of styrene in the presence of diethylazoacetate. Data reveal that insoluble systems prepared by polymerization are much moreeffective that those prepared by grafting. The best performances, in particular in terms ofselectivity, were obtained for tert-butylglycine-derived systems. In some cases, functional resinsthat are more active, chemoselective, and enantioselective than the corresponding homogeneousanalogue systems have been obtained. The presence of additional functionalities in the polymericmatrix is, in general, detrimental for the performance of the supported catalyst, even if thepresence of more flexible cross-linkers enhances the accessibility of the functional sites. TheCopper bis(oxazoline) polymeric systems are easily recycled and reused and provide materialsof high utility for their use in facilitated chemical synthesis.