Synthesis and applications of cinchona squaramide‐modified poly (glycidyl methacrylate) microspheres as recyclable polymer‐grafted enantioselective organocatalysts

Nagy, Sándor and Fehér, Zsuzsanna and Kárpáti, Levente and Bagi, Péter and Kisszékelyi, Péter and Koczka, Béla and Huszthy, Péter and Pukánszky, Béla and Kupai, József (2020) Synthesis and applications of cinchona squaramide‐modified poly (glycidyl methacrylate) microspheres as recyclable polymer‐grafted enantioselective organocatalysts. CHEMISTRY-A EUROPEAN JOURNAL. ISSN 0947-6539

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Abstract

Our work presents the immobilization of cinchona squaramide organocatalyst on poly(glycidyl methacrylate) solid support. Preparation of the well-defined monodisperse polymer microspheres was facilitated by comprehensive parameter optimization. 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 Michael addition reaction of pentane-2,4-dione and trans--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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