An Fmoc-protected L-serine building block carrying a β-D-galactose residue, designed for solid-phase peptide synthesis (SPPS) of glycopeptides. The Nα-Fmoc group is removed under standard base conditions (piperidine) during chain elongation, while the free α-carboxylic acid is available for coupling to the growing resin-bound peptide. The sugar hydroxyl groups are protected as four acetate esters (Ac4), which keep the glycan inert during synthesis and are removed under mild base (e.g., sodium methoxide / hydrazine) after assembly. The installed glycan is a galactose residue, serving as a model glycoamino acid for glycopeptide synthesis and a substrate for galactose-recognizing lectins (e.g., galectins) and glycosidases.