Constructing Chiral Porous Organic Bolymers For Heterogeneous Asymmetric Organocatalysis

Due to their inherent porosity, large specific surface area, light weight, and easy functionalization at the molecular level, porous organic polymers have recently received significant attention for potential applications in gas storage/separation, light-harvesting, sensoring, and heterogeneous catalysis. Especially, the construction of functional porous organic polymers via bottom-up strategy for heterogeneous catalysis has made tremendous development in recent years. The reported research works in this field are mainly focused on the embedding of the organometallics into the polymers, or the encapsulation of the metal particles into the porous organic polymers. Nevertheless, to date, the embedding of chiral organocatalysts into the frameworks of the porous organic polymers via bottom-up strategy has been not reported yet. In this context, with the rapid development of asymmetric organocatalysis, construction of organocatalysts embedded chiral porous organic polymers via bottom-up strategy for the heterogeneous asymmetric organocatalysis will be a promising and challenging research issue.Accordingly, the main research contents of this thesis is to design, synthesize and characterize the chiral porous organic polymers based on chiral organocatalysts (J(?)rgensen-Hayashi catalyst and MacMillan catalyst), and utilize them in the heterogeneous asymmetric organocatalysis. The main achievements of this thesis could be divided into the following four parts:1. The Jorgensen-Hayashi catalyst has been successfully embedded into a nanoporous polymer via the bottom-up strategy. The obtained JH-CPP polymer has been utilized as a highly efficient heterogeneous organocatalyst for the asymmetric Michael addition reaction. Owing to the high BET surface area (881m2/g), as well as the widely pervasive and interconnected pores, JH-CPP possesses comparable activity and enantioselectivity with the homogeneous JH catalyst. Furthermore, the JH-CPP catalyst can be reused for at least four times with no decrease of enantioselectivity (97-99%ee).2. To further expanding the catalytic application of JH-CPP to other asymmetric reactions, we have also applied JH-CPP as the heterogeneous organocatalyst in the asymmetric Michael addition reaction of nitromethane with a, p-unsaturated aldehydes. The JH-CPP catalyst shows comparable catalytic efficiency with the homogeneous JH catalyst, and can be reused for at least six times with no decrease of enantioselectivity (95-96%ee). Notably, the catalytic efficiency of JH-CPP catalyst is superior to that of the traditional immobilized J(?)rgensen-Hayashi catalyst.3. The MacMillan catalyst has been successfully embedded into nanoporous polymers via the bottom-up strategy, and the obtained polymers have been applied as highly efficient heterogeneous organocatalysts for the asymmetric Diels-Alder reaction. The specific surface areas of the three MacMillan catalyst-embedded chiral porous polymers (Mac-CPP-1, Mac-CPP-2, Mac-CPP-3) can be adjusted by changing the size of the structural building blocks. We have also investigated the structure-property-catalytic activity relationship of these MacMillan catalyst-embedded chiral porous polymers.4. We have synthesized a "self-supported" polymeric MacMillan catalyst (Mac-ChiOSP), which can be applied as an efficient catalyst for homogeneous organocatalysis and heterogeneous recycling for the asymmetric Diels-Alder reaction. In comparison with thosee immobilized MacMillan catalysts, this "self-supported" polymeric MacMillan catalyst possesses homogeneously-distributed and highly-concentrated catalytic sites. This advantage together with the homogeneous catalytic nature ensured its excellent catalytic ability. Furthermore, the heterogeneous catalyst can be reused for at least three times with no decrease of enantioselectivity (86-90%ee for endo,84-88%for exo).