Polymer-Supported Bis(oxazolines) and Related Systems:  Toward New Heterogeneous Enantioselective Catalysts

• Published in: Industrial & engineering chemistry research 2005-11, Vol.44 (23), p.8580-8587
• Main Authors: Burguete, M. I, Fraile, J. M, García-Verdugo, E, Luis, S. V, Martínez-Merino, V, Mayoral, J. A
• Format: Article
• Language: English
• Subjects: Applied sciences; Catalysis; Catalytic reactions; Chemical engineering; Chemistry; Exact sciences and technology; General and physical chemistry; Reactors; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie0488288

Polymer-supported bis(oxazoline) and related ligands have been prepared by grafting and by polymerization methodologies under a variety of conditions. The corresponding Cu complexes have been assayed as catalysts for the cyclopropanation of styrene in the presence of diethyl azoacetate. Data reveal that insoluble systems prepared by polymerization are much more effective that those prepared by grafting. The best performances, in particular in terms of selectivity, were obtained for tert-butylglycine-derived systems. In some cases, functional resins that are more active, chemoselective, and enantioselective than the corresponding homogeneous analogue systems have been obtained. The presence of additional functionalities in the polymeric matrix is, in general, detrimental for the performance of the supported catalyst, even if the presence of more flexible cross-linkers enhances the accessibility of the functional sites. The Copper bis(oxazoline) polymeric systems are easily recycled and reused and provide materials of high utility for their use in facilitated chemical synthesis.