Synthesis Of Glycosyl Ester And N-linked Carbohydrate In Ionic Liquids

Ionic liquids show an enhanced performance in organic chemistry involving carbohydrate chemistry when compared to the conventional organic solvents owing to their some attractive features:simple handing, high-yield, short reaction time, environmentally friendly, ease of synthesis and excellent recyclability. Carbohydrates are not only known for their significant commercial applications as foods, drugs and chemical feed stocks etc., but suger based moleculars are also indentified to play vital roles in pathologically and physiologically important biological processes.The graduate work is a research on methodology study of glycosyl ester and N-linked carbohydrate in ionic liquids. Glycosyl esters are not only known for the glycosylation donor, but the esters are also indentified to be transformed into other types of glycosylation donors to efficiently construct new glycosylation reaction. Many natural product molecules containing carbohydtrate-ester bond possess excellent biological activitities and pharmacological effects. So constructing carbohydrate-ester bond is applied to the total synthesis of natural products. The first part is the investigation on glycosyl ester. We performed ionic liquids as solvents, silver oxide as a catalyst, quaternary ammonium salts as additives with high yield without dry and oxygen-free handling in order to avoid using intractable high boiling point solvents and air-free technique. We found that quaternary ammonium salts could inhibit the generation of by-products. Substances with electron-donating group is better than ones with electron-withdrawing group in yields. The types of substances can be aromatic (including anise) and aliphatic family. Then we obtained two single crystal structures(one is aliphatic ester, the other is aromatic ester) which confirmed the β configuration. We also analysed some data on the aliphatic crystal structure. comparing the ionic liquid method with other three synthesizing carbohydrate-ester methods in aliphatic ester discuss, the effect of the ionic liquid method is obviously better than other methods. And later the ionic liquid is testified to recycle. We extended the fifteen substrate moleculars.The second part is research on N-linked carbohydrate. Study of N-linked carbohydrate in ionic liquid proved that the reaction could be run without any other catalyst. Maybe ionic liquid participate in the reaction as "some" catalyst. The effect of electron-donating group is significantly better than the electron-withdrawing group in yields. Generally, The condition of reaction was mild and green without heating or cooling. From’H NMR and13C NMR analysis, we confirmed the β configuration of the product along with extending the thirteen substrate moleculars. N-linked carbohydrate bond is an pivotal group of biological molecules as nucleic acids and glycoproteins. Research on N-linked carbohydrate bond is not only known for chemical methodology and total synthesis. But also it is significant to life science.