A fully unprotected (free amine, free acid) L-serine glycoamino acid carrying an α-D-galactose residue. This deprotected building block is suited to use as a reference standard, an enzymatic substrate/acceptor, or for conjugation and analytical work rather than direct Fmoc-SPPS. 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.