Stereoselective Ferrier‐Type O ‐Glycosylation Enabled by Difluoromethylated Glycal Donors

Abstract The effective construction of structurally homogeneous glycosides is requisite in oligosaccharide assembly and the development of carbohydrate‐based drugs. A fluorine‐mediated stereoselective Ferrier‐type glycosylation is reported herein. Glycals are pre‐decorated with photo‐2‐difluoroalkylation and reacted with diverse acceptors to obtain exclusively α‐selective Ferrier rearrangement products. This procedure can tolerate extensive substrates and achieve good yields. Subsequent gram‐scale and oligosaccharide syntheses further demonstrate the applicability and practicality of this strategy. Detailed density functional theory studies demonstrate the predominant stereoselectivity of the glycosylation process.