Synthesis And Applications In Asymmetric Catalysis Of Chiral Sulphur And Phosphorous Ligands

Material all has the symmetry from ancient times to the present, we live in a symmetric world. However, with the development of science, the asymmetric phenomenon is also coming into sight, to astronomy and geography, even if to a chemical molecule. The molecules made up of the two same elements can present great differences in its optical properties and physiological activity, due to the differences in the spatial configuration. There are a lot of chiral drugs have been discovered with the discovery of these differences. The synthesis of chiral compounds become a hot topic in the present, however, the catalytic asymmetric synthesis will undoubtedly become the best prospects method because of its amplifying role in the all synthetic methods. But, in this filed the research and development of new chiral ligands has been a hot topic and challenges. Therefore, this paper mainly discusses the synthesis of some new chiral ligands and studies the application of them in asymmetric synthesis. The specific contents are as follows:Four ligands bearing pyridyl or imine N were prepared by a condensation of ketones or aldehydes with chiral 2-methylpropane-2-sulfinamide. The synthesized ligands were used in Henry reaction and aza Henry reaction with different copper as catalyst. After a series of attempts, we found optimal conditions for Et3 N content 15%, using tetrahydrofuran as solvent, and at room temperature. The catalytic reaction can be finished in 30 min, and the product can be obtained in 99% yield with a lower enantio-selectivity 7%ee.C2 symmetric olefin,S-ligands were prepared from(R,R)--1,2-diphenylethane-1,2-diamine by alkylation of amine and the reaction of diamine with sulfurous dichloride. The chiral olefin,S-ligands were used in rhodium catalyzed 1,4-addition of aryl boronic acids to a,b-carbonyl compounds. The product of catalytic reaction can be obtained in 99% yield higher to excellent selectivity under the condition of dioxane as solvent and KOH as base with the temperature of 60 ℃. The stereochemical model was rationalized according to the absolute con?guration of adducts.The trans olefins,P- ligand were prepared from(S)-tert-butyl 2-(hydroxymethyl) pyrrolidine-1-carboxylate by oxidation, Horner-Wadsworth-Emmons olefination reaction of the aldehyde, removal of the tert-butoxycarbonyl group and the subsequent N-phosphination with chlorodiphenyl phosphine. The chiral olefin, P-ligands were used in rhodium catalyzed asymmetric addition of aryl boronic acids to electron-deficient olefins. The adducts of a,b-carbonyl compounds can be obtained in high yield with excellent enantio-selectivity under the condition of dioxane as solvent and KOH as base with the room temperature. The addition product of nitroolefin can be gained in 80% yield with 70% ee.In this paper, thirteen chiral ligands were synthesized, and their applications to asymmetric reactions were achieved with good yields and selectivity, and it provided a wider application for asymmetric catalytic reactions.