Highly Reactive\nGlycosylation\nwith 1-<i>O-</i>(Methylthio)thiocarbonyl Glycosyl Donors\nunder Acidic to Neutral\nReaction Conditions

In this study, we have successfully\ndeveloped a glycosylation method\nusing 1-<i>O</i>-(methylthio)thiocarbonyl–glycoses\nas donors. Such xanthate donors are easily accessible and shelf-stable.\nThe glycosylation reaction could be promoted by cations (acidic to\nneutral conditions) under mild conditions, exhibiting a reactivity\nintermediate between that with glycosyl trichloroacetimidate as the\ndonor and that with thioglycoside as the donor. This methodology tolerates\nboth “armed” and “disarmed” glycosyl donors,\nas well as various sugar acceptors, and affords the corresponding\nglycosides in good to excellent yields. Based on the relative higher\nreactivity of such xanthate donors than thioglycoside donors under\nthe same glycosylation conditions, a trisaccharide was further synthesized\nin a one-pot glycosylation strategy.