Gold-catalyzed Synthesis Of ?-Glucan

?-Glucan is a polysaccharide found in bacteria,fungi,algae and plants.It is a polymer linked by ?-D-glucose through ?-(1,3)-glycosidic bonds,and some also contain ?-(1,6)-glycosidically linked branches.A variety of ?-glucan receptors are contained in mammals,and there are known as lactosylceramides,scavenger receptors,CR3 and Dectin-1.?-Glucan can be recognized by the innate immune system through interaction with these receptors,producing immunomodulatory,anti-tumor,antibacterial,anti-fungal and anti-viral activities.Among these four receptors,Dectin-1 appears to be the major receptor for ?-(1,3)-glucan and is capable of mediating many biological activities of ?-glucan.In this study,we used ?-(1,3)-hexadeca-saccharide as our target molecule.We plan to adopt a glycoylation method of gold-catalyzed o-alkynyl benzoate to construct glycosidic bonds,and to efficiently prepare ?-(1,3)-hexadeca-saccharide.First,we protected the hydroxyl groups of ?-D-glucose with different groups,and the 2-OH used the ortho position of benzoyl group to control the ?-configuration.The block is then made into an o-alkynyl benzoate donor,using a gold-catalyzed glycosylation method according to[1+1],[2+2],[4+4],[8+8]synthesis method efficiently providing ?-(1,3)-hexadeca-saccharide.Finally,we succeeded in obtaining ?-(1,3)-hexadeca-saccharide with high yield.We protect the anomeric position with a methoxy group and remove all protecting groups to get the final target molecule.In the future,we will determine its biological activity and assess its potential as carbohydrate-based drug candidate.