Application Of Guanosine Borate G-quadruplex Supramolecular Hydrogel In Asymmetric Catalysis

The asymmetric Aldol reaction is an important method for the preparation of complex chiral compounds.The classic proline organic small molecule catalyst is restricted by its dependence on the organic solvent reaction medium and does not conform to the concept of "green chemistry".Taking environmental,safety and cost factors into consideration,a catalyst that can maintain high catalytic performance in a pure water phase environment and achieve high-efficiency separation from the product is the design goal of the new Aldol reaction catalyst.In this thesis,inspired by proline acetalase,proline was covalently modified into G-quadruplex supramolecular hydrogel with uniform and ordered hydrophobic structure to construct a supramolecular catalyst,which showed a highly efficient asymmetric Aldol reaction catalyst in the aqueous phase.In this paper,a G-quadruplex supramolecular hydrogel GBPK modified with proline functional groups was designed.The physical and chemical properties of GBPK self-assembly were discussed in detail by methods such as VT-NMR,CD,electron microscopy,and FTIR.The relationship between the stability of the super-assembly and the cation species,component concentration,and temperature was explored.The supramolecular catalytic system constructed by GBPK realized the catalysis of asymmetric Aldol reaction in pure water medium and achieved good enantioselectivity.Under the optimal conditions,the catalytic ee value of substrate 1a can reach 91.49%,which is much higher than the ee value of about 45%in the small molecule control group.It’s showed that the stable supramolecular assembly has a decisive effect on high enantioselectivity.in addition,the GBPK supramolecular catalyst showed good performance when using different substrates for the Aldol reaction.The catalytic system maintained high ee value during the four consecutive reaction processes,showed good recycling performance.This work designed a new type of asymmetric Aldol reaction catalyst,verified the functional consistency of the G-quadruplex supramolecular hydrogel and the relatively complex G-4 DNA molecular scaffold in the asymmetric catalytic reaction,and expanded the supramolecular The design ideas,enriched the application range of supramolecular hydrogels based on guanosine and its derivatives.It is pointed out that further improving the stability and chiral structure of the assembly is the optimal direction for the application of G-quadruplex supramolecular hydrogels in asymmetric catalytic reactions.