Title: Immobilization of cinchona squaramide organocatalysts on poly(glycidylmethacrylate) and their application

Abstract:

Owing to their successful application in asymmetric reactions, cinchona-based organocatalysts are widespread in the field of homogenous organocatalysis. They are applied in asymmetric reactions such as Michael addition, Morita–Baylis–Hillman and Diels–Alder reactions with high yields and enantiomeric excesses. Since the recovery of homogeneous catalysts is essential for their economical application, immobilization on polymer support promises a solution for reusing them. Herein this work presents the preparation of a polymer carrier and, the synthesis and application of immobilized cinchona squaramides. Non-immobilized cinchona squaramides were tested in seven different solvents with excellent yields (up to 99%) and enantiomeric excesses (up to 91%),1 therefore this catalyst was chosen to immobilize on a carrier. As polymer support, poly(glycidyl methacrylate) (PGMA) microspheres were prepared by radical dispersion polymerization. As a result, polymer particles were obtained with narrow size-distribution (~1 m) furthermore, their resistance to solvents and mechanical damage was increased by subsequent cross-linking. By taking advantages of reactive epoxy-groups, cinchona squaramide was immobilized on PGMA via linker containing primer amino groups, which readily reacts with epoxides. Two PGMA immobilized catalysts were prepared (see Figure 1): in one, cinchona squaramide was immobilized so the linker connects at quinoline (left) while, in the other it connects at quinuclidine group (right). After their activity was compared in Michael addition reaction in batch using two different solvents, the one that performed better was chosen to use in a continuous flow reactor consisting of a column filled with the immobilized catalyst. The performance of the immobilized catalyst was examined in Michael addition reaction in the continuous flow reactor. This research was funded by the New National Excellence Program of the Ministry of Human Capacities, grant number ÚNKP-19-3-I-BME-397, ÚNKP-19-4-BME-415, and the Janos Bolyai Research Scholarship of the Hungarian Academy of Science. It was also supported by the National Research, Development and Innovation office (former OTKA, grant number K128473).

Biography:

Sándor Nagy is a third year PhD student at the George Oláh Doctoral School, Budapest University of Technology and Economics, Hungary. He works under the supervision of Dr. József Kupai in the Organocatalysis Research Group (www.kupaigroup.com) at the Department of Organic Chemistry and Technology. His research focuses on design, synthesis, application and recycling of cinchona-based organocatalysts.