Fmoc-Phe(3-NO2)-OH is primarily used in peptide synthesis, particularly in solid-phase peptide synthesis (SPPS). It serves as a protected amino acid building block, where the Fmoc group provides temporary protection for the amino group during the synthesis process. The nitro group on the phenyl ring can be utilized for further chemical modifications or as a spectroscopic probe due to its distinct electronic properties. This compound is valuable in the production of peptides with specific functional or structural features, often employed in research to study peptide interactions, enzyme activity, or as intermediates in the development of pharmaceuticals. Its unique structure allows for the incorporation of nitro-aromatic properties into peptides, which can be useful in designing bioactive molecules or probes for biochemical studies.