Preparation Of Proline - Derived Secondary Amines Catalyzed By Novel Core - Shell And Shell Polymer And Its Application In Asymmetric Series Reaction

Owing to the environment-friendly and metal-free advantages, recently developed organocatalys becomes one of hot topics in the field of asymmetric catalysis. However, the recovery strategy and heterogeneous catalytic system with high catalytic performance, especially for multicomponent heterogeneous catalytic system, became a new challenge for scientific investigators. In this paper, based on the concept of green chemi- stry, a core-shell and hollow polymer-supported J?rgensen–Hayashi organocatalyst was developed to improve catalytic efficiency of supported organocatalyst and achieve heterogeneous multi-component organocascade with high excellent performance.In this paper, using Boc-L-proline as starting material, three types of heterogene- ous J?rgensen–Hayashi organocatalysts, copolymer-supported Poly(St/ProTMS), core- shell PS@ProTMS CSNs and hollow AM/ProTMS HNs, were prepared through meth- ylation, nucleophilic addition, deprotection and substitution reactions. Their composi- tions, structures and morphologies were characterized by SEM, N2 adsorption–desorp- tion isotherm, TG and TEM.Using asymmetric three-component tandem reaction of trans-nitrostyrene, cinnamic aldehyde and propionaldehyde as a model reaction, the effects of different reaction temperature, solvent, dosage of catalyst on catalytic performance were investigated, and the best reaction conditions were screened out. It was found that AM/ProTMS HNs(4/b) possessed the best catalytic performances and achieved the same level of catalytic performances in Michael/Michael/aldol tandem reaction(32–60%,dr = 80–93/7–20,≥99% ee). After completion of the reaction, the catalyst could be recovered by simple filtration or centrifugation. The stereoselectivities of AM/ProTMS HNs(4/b) were maintained as its original stereoselectivities. Unfortunately the gradually decreased yields were observed in first three times.