Fmoc-4-Chloro-D-Phe-OH is widely used in peptide synthesis as a building block. Its Fmoc (fluorenylmethyloxycarbonyl) protecting group allows for selective deprotection during solid-phase peptide synthesis, enabling the stepwise assembly of peptides. The 4-chloro substitution on the phenylalanine side chain introduces hydrophobicity and steric effects, which can influence peptide structure and function. This compound is particularly valuable in creating peptides with specific biological activity, such as receptor binding or enzyme inhibition, and is often employed in drug discovery and biochemical research. Its chiral nature (D-configuration) is useful for studying peptide stereochemistry and designing peptidomimetics with enhanced stability or selectivity.