Synthesis And Asymmetric Catalytic Behaviors Of Chiral Imine And Dimines Schiff Bases

Chirality is one of the basic properties of nature, which play a very important role in biology, medicine, etc. Hence, design and synthesis of high catalytic activity and enantioselectivity of chiral catalysts is one of the hottest research topics. A lot of ligands, such as amino alcohol, N, P ligands,N, S ligands, P, P ligands, have been widely used as the chiral catalysts. The monoamine and diamine based on the chiral Schiff base ligands and their catalytic application have been rarely reported.Based on the above background, a total of 12 chiral ligands based on L-menthol and various amines were synthesized and their catalytic classic asymmetric syntheses were studied. The details are as follows:Firstly, the background and development are described:(1) the development, synthesis, selection, and application of Schiff base; (2) research progress of chiral Schiff base in catalytic asymmetric reactions.Secondly,9 chiral Schiff base ligands were prepared by dehydration condensation of L-menthol and a variety of primary amines. Three of them were reduced to form chiral amine ligands by NaBH4.Thirdly,12 chiral catalysts were employed to catalyze the following three classical catalytic reactions:(1) Reformatsky reaction, (2) enantioselective addition of diethylzinc to benzaldehyde, (3) enantioselective addition of n-BuLi to benzaldehyde. The reaction conditations were optimized and the products were characterized by high performance liquid chromatography.