A β-D-galactose ligand equipped with a thiol-functionalized linker through a short ethyl spacer. The thiol group can be reacted with other thiol-modified substrates to form disulfide bonds, or reacted with maleimides to form stable thioether conjugates. This compound provides a β-anomeric galactose building block for glycoconjugate synthesis, glycomimetic research, and the construction of probes for galactose-recognizing proteins, including galectins and other carbohydrate-binding lectins. Terminal β-Gal residues are also a substrate for glycosyltransferases, including sialyltransferases and fucosyltransferases, enabling enzymatic chain extension.