Total Synthesis Of Natural Phenylethanoid Glycosides By Interrupted Pummerer Reaction Mediated Glycosylation

Phenylethanoid glycosides are a group of natural glycosides with a substituted phenylethyl alcohol or its analog as aglycon,they are widely distributed in dicotyledons,and present various bioactivities,such as antioxidation,hepatoprotection,anti-tumor effect and so on.Despite their important bioactivities,phenylethanoid glycosides are tedious to isolate from natural plants since they are commonly accompanied with polysaccharides,iridoids or lignins during the separating process.Thus,it is quite meaningful to develop an efficient chemical synthetic strategy towards phenylethanoid glycosides.Interrupted Pummerer reaction mediated glycosylation is developed by our group in recent years,this newly developed method is outstanding for adopting the latent-active strategy and activating in a remote manner,it also presents the advantages of efficient activation,wide scope of substrates,easy obtained glycosyl donors and so on.Due to these features,interrupted Pummerer reaction mediated glycosylation is quite desirable in total synthesis of complex glycosyl molecules.In this thesis,we described the diversified synthesis of 8 natural phenylethanoid glycosides and 2 their analogs by interrupted Pummerer reaction mediated glycosylation method.These 10 compounds include 4 phenylethanoid disaccharides,4 linear phenylethanoid trisaccharides and 2 branched phenylethanoid trisaccharides.Meanwhile,we accomplished the structure revision of Leonoside E from Leonurus japonicas Houtt.,and we researched on the exploration of the exact structure of “Leonoside F” from Rehmannia glutinosa.In conclusion,we accomplished the synthesis of a series of phenylethanoid glycosides in this research which is quite meaningful for the related bioactivity studies.This research also proves the practical applicability of the newly developed interrupted Pummerer reaction mediated glycosylation method,and provided a reference for the synthesis of more complex natural phenylethanoid glycosides and glycoconjugates.