Fmoc-D-4-Hydroxyphenylglycine is widely used in peptide synthesis as a building block. It is particularly valuable in solid-phase peptide synthesis (SPPS) due to its Fmoc protecting group, which can be easily removed under mild basic conditions. This compound is often employed in the synthesis of complex peptides and proteins, especially when incorporating D-amino acids or hydroxyl-containing residues is necessary. Its application extends to the development of peptide-based drugs, biomaterials, and research tools, where precise control over peptide structure and function is critical. Additionally, it is utilized in the study of enzyme mechanisms and protein-protein interactions, as well as in the creation of peptide libraries for drug discovery.