Stereoselective Synthesis Of 2-Deoxy-?-Glycosides

2-Deoxy sugars are not only a component of natural products and clinical medicines,but also the necessary building blocks for their biological activities.However,the content of 2-deoxyglycosides in natural products is very low and the forms are complicated.It is difficult to obtain a sufficient amount of 2-deoxyglycosides with high-purity by natural extraction methods,which greatly limit its application in medicine.Hence,it becomes necessary to synthesize 2-deoxyglycosides by chemical approaches.Nevertheless,due to the lack of stereoselective directing group in the C-2 position and the unstability of glycosidic bond,the stereoselective synthesis of 2-deoxyglycosides are very challenging.Compared to direct strategy,indirect strategy is the most efficient method for highly stereoselective synthesizing 2-deoxy-?-glycosides.However,in indirect methods,the introduction reactions of iodine atom are inefficient and the separation of products is difficult.In addition,the removal reactions of iodine atom always use toxic reagents or the efficiency is low.These factors greatly limit the synthesis of 2-deoxy-?-glycosides,especially bioactive 2-deoxy-?-glycosides.Based on photocatalysis mild and efficient feature,we developed a novel visible-light mediated deiodination reaction.It was found that p-toluenethiol was the hydrogen donor and electron donor for the reaction.Finally,this method was successfully applied in deiodination of various iodides,which laid the foundation for the synthesis of 2-deoxy-?-glycosides.In this thesis,we used indirect synthetic method to accomplish the synthesis of diversified 2-deoxy-?-glycosides,which provided a new alternative for the synthesis of biologically active complex natural products and drug molecules.In addition,this method laid the foundation for future study on glycobiology and carbohydrate-based drugs.