Parallel Synthesis Of Steroidal Saponins

The molecular diversity of sugars has been recognized in their involvement in many important biological processes. The efficient synthesis of oligosaccharides for study of their structure function is, however, still a very significant challenge because of the restriction from traditional synthetic methods and the nature of sugars. Focused on the problems aboved, many approaches were developed in the field of carbohydrate and parallel synthesis was the most attractive one. Steriodal saponins are largely distributed in terrestrial plants and some marine organisms. Many traditional Chinese herbs containing steroidal saponins as main active components were widely used in folk medicine. Many study results have disclosed that both the modification of the sapogenin and the change of sugar chain will have a notable effect on their bioactivities, absorption, distribution and metabolism. Because of the difficulty in isolation of homogeneous saponins from plants, it was not get along well with the study of structure-activity relationships about saponin, nor explore the biochemical mechanism of herb with saponin as main component, nor develop the new lead compound with the structure of saponin.The research topic in the thesis was focused on above aspect involving synthesis of a series of structural homogeneous saponins via parallel synthesis.1. Design and synthesis of a series of novel tigogenyl glucosides.To study the structure-activity relationships on tigogenyl glycosides containing N-acetylglucosamine, a series of novel tigogenyl saponins were designed. From a synthesized building block with phthalimido, benzyl, chloroacetyl and tert-butyldimethylsilyl as orthogonal protective groups, one monosaccharide saponin, seven disaccharide saponins, four trisaccharide saponins were facile synthesized via parallel synyhesis.