A fluorinated N-acetylgalactosamine analog in which the C4 hydroxyl is replaced by two fluorines (gem-difluoro). Fluorinated GalNAc analogs are valuable probes for studying GalNAc-processing enzymes (glycosyltransferases, glycosidases, and the GalNAc salvage pathway), as metabolic inhibitors of mucin-type O-glycan and glycosphingolipid biosynthesis, and as tools for investigating lectin recognition (e.g., MGL, ASGPR). The carbon-fluorine bond is stable, isosteric with the native hydroxyl, and provides a handle for ¹⁹F NMR studies of glycan-protein interactions.