Used in peptide synthesis as a chiral building block for introducing amino acid derivatives with specific stereochemistry. The presence of the Fmoc group allows for orthogonal protection in solid-phase peptide synthesis, enabling stepwise assembly of peptide chains. The 4-nitrophenyl group provides a handle for monitoring reactions due to its UV absorbance, useful in analytical and purification steps. Commonly employed in the preparation of peptidomimetics and bioactive molecules where stereocontrol is critical.