Chiral Thiourea Organocatalysts Catalyzed Aza-Henry Reaction And Extraction And Purification Of Stilbene Glucoside

In this thesis, the work covers two parts as follows:The first is about asymmetric Aza-Henry reaction. Catalytic asymmetricsynthesis is one of the most efficient method to synthesize optical pure compounds,in which a good deal of chiral adducts were obtained with a little amount of chiralcatalysts. Asymmetric Aza-Henry reaction is one of the most important methods toform new carbon-carbon bonds in organic synthesis. The resulting β-nitronitroamine adducts can be easily converted into some important building blocks,such as1,2-diamines，amino acids.The catalysts of asymmetric synthesis include metal complexes andorganocatalysts which are both useful and effective catalysts. Among theorganocatalysts, chiral thiourea has been gained increasing interests due to itssimple preparation and efficient activation of reactants via hydrogen bond. In thisthesis, a novel type of bifunctional chiral thiourea organocatalysts has beendeveloped, which were readily synthesized from inexpensive natural amino acids and cinchona alkaloids. Those thiourea catalysts were succefully applied to theasymmetric Aza-Henry reaction of N-Boc imines with nitroalkane.As the result, under the selected optimal conditions, we found that46h wasthe most outstanding one. This reaction can ran smoothly to afford thecorresponding R-configuration adducts in good to excellent yields (up to90%) andwith good enantioselectivities (up to99%ee). When nitromethane was used, theproducts could be achieved with up to17:1dr,99%ee and85%yield.This newcatalyst system for the asymmetric Aza-Henry reaction is valuable due to its highefficience, excellent enantioselectivity, mild conditions and low cost.The second part is about extraction and purification of stilbene glucosidefrom Polygonum Multiflorum Thunb. The Polygonum Multiflorum Thunb (PM) isan earthnut plant of Polygonaceae herbaceos perennial and is typically traditionalanti-aging herb in China.The tetrahedroxy stilbene glucoside (TSG) is the mainly bioactivitycomponent of PM. Because of its much biological activity, TSG showedpromissing potential for treat with Vascular Dementia. The instability property ofTSG makes the extraction and purification of stilbene glucoside from PolygonumMultiflorum is of a great challenge. Reports about the method of extraction andpurification of stilbene glucoside are all involving with the columnchromatography to separate, but they all have such problems as great consumingof solvent, limitation for amplification etc. We try to find a direct and easy way toextraction and purification of stilbene glucoside.The work in this thesis presented an improved process for the extraction andpurification of stilbene glucoside from Polygonum Multiflorum Thunb. Ethanolwas used as the solvent to extract TSG from PM, followed by extraction, acid-basetreatment, salt-forming method and crystallization afforded the TSG with a purity of99%. This process is simple and can be amplified in an industrial scale.