Synthesis and Applications of Cinchona Squaramide-Modified Poly(Glycidyl Methacrylate) Microspheres as Recyclable Polymer-Grafted Enantioselective Organocatalysts |
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Authors: | Sándor Nagy Zsuzsanna Fehér Levente Kárpáti Dr Péter Bagi Péter Kisszékelyi Dr Béla Koczka Prof Péter Huszthy Prof Béla Pukánszky Dr József Kupai |
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Institution: | 1. Department of Organic Chemistry & Technology, Budapest University of Technology & Economics, Szent Gellért tér 4, 1111 Budapest, Hungary;2. Laboratory of Plastics & Rubber Technology, Budapest University of Technology & Economics, Műegyetem rkp. 3., Budapest, 1111 Hungary;3. Department of Inorganic and Analytical Chemistry, Budapest University of Technology & Economics, Szent Gellért tér 4, 1111 Budapest, Hungary |
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Abstract: | This work presents the immobilization of cinchona squaramide organocatalysts on poly(glycidyl methacrylate) solid supports. Preparation of the well-defined monodisperse polymer microspheres was facilitated by comprehensive parameter optimization. By exploiting the reactive epoxy groups of the polymer support, three amino-functionalized cinchona derivatives were immobilized on this carrier. To explore the effect of the amino linker, these structurally varied precatalysts were synthesized by modifying the cinchona skeleton at different positions. The catalytic activities of the immobilized organocatalysts were tested in the Michael addition of pentane-2,4-dione and trans-β-nitrostyrene with excellent yields (up to 98 %) and enantioselectivities (up to 96 % ee). Finally, the catalysts were easily recovered five times by centrifugation without loss of activity. |
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Keywords: | immobilization Michael addition organocatalysis polymers recycling |
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