Total Synthesis Of Some Active Glycoconjugates

Steroidal glycosides widely occur as natural products. They act as active compounds of many medical plants and exhibit various bioactivities. In this thesis three molecules of steroidal glycosides and glycolipid which either have good bioactivities or have unique structure were synthesized. The methods and strategies used in this thesis can be used again in the synthesis of these types of molecules and the synthesis can serves as a basis for testing their bioactivities, revealing the relationships between structure and bioactivity.Saponins containing N-acetylglucosamine are very important saponins. Though N-acetylglucosamine containing saponins are rare, they all have good bioactivities, especially anticancer activities. So far no paper was published about the synthesis of this type of saponins. Employing glycosyl trifluroacetimidates and thioglycoside, we finished the synthesis of the target molecule in a stepwise fashion. Because the structures of this type of saponins are highly conservative, the synthesis of target molecule can be regardde as reference to the synthesis of N-acetylglucosamine containing saponins.Caminoside A, a novel antimicrobial tetrasaccharide glycolipid from marine sponge, which represents the first bacterial type III secretion system inhibitor (TTSS), is synthesized in a total of 57 steps starting from D-glucose, D-galactose, L-rhamnose, and 9-decenal. In the synthesis of Caminoside A, construction of the 1,2-cis-β-manopyranoside-type linkage of the 6-deoxy-talose is achieved by oxidation-reduction sequence. From the results which are get from my experiments and from references, we draw some primary conclusion about...