An Fmoc-protected L-serine building block carrying a β-D-lactose (Galβ1-4Glc) disaccharide, 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 seven acetate esters (Ac7), 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 lactose (Galβ1-4Glc) disaccharide, a model building block and galectin-binding ligand for glycopeptide synthesis.