1,2-cis-α-Stereoselective Glycosylation Utilizing a Glycosyl-Acceptor-Derived Borinic Ester and Its Application to the Total Synthesis of Natural Glycosphingolipids

1,2-cis-alpha-Stereoselective glycosylations were conducted using a 1,2-anhydroglucose donor and mono-ol acceptors in the presence of a glycosyl-acceptor-derived borinic ester. Reactions proceeded smoothly under mild conditions to provide the corresponding alpha-glycosides with high stereoselectivity in moderate to high yields. In addition, the present method was applied successfully to the direct glycosylation of a protected ceramide acceptor and the total synthesis of natural glycosphingolipids (GSLs).