Syntheses of fluorinated mucin core 6 disaccharides and core 2 trisaccharides modified at the C-3 or C-4 position of the pertinent glucosamine residue required for mechanistic study of glycosyltransferases and sulfotransferases involved in the biosynthesis of O-glycans are reported. Novel fluorinated glucosaminyl donors were synthesized from 2-naphthylmethyl β- dN-acetylglucosamine (β-O-NAP-GlcNAc) via double inversion of the C-3 or C-4 ...