Journal of Catalysis, Vol.377, 543-549, 2019
Design and synthesis of chiral hyperbranched polymers containing cinchona squaramide moieties and their catalytic activity in the asymmetric Michael addition reaction
Chiral hyperbranched polymers (HBP) containing cinchona alkaloids were synthesized using a Mizoroki-Heck (MH) coupling polymerization reaction between a cinchona squaramide dimer and tri- or tetrasubstituted aromatic iodides. This is a new type of polymeric chiral organocatalyst. We found that the as-obtained chiral HBPs show excellent catalytic activity in the asymmetric Michael reaction. Almost perfect enantioselectivity (>99% ee) was achieved in the reaction of beta-ketoester and trans-beta-nitrostyrene. The three-dimensional network structure of the chiral HBPs is structurally robust and can be reused for further reaction without any loss in their catalytic activity. (C) 2019 Elsevier Inc. All rights reserved.
Keywords:Chiral hyperbranched polymer;Cinchona squaramide;Mizoroki-Heck polymerization;Asymmetric Michael reaction