Used in peptide synthesis to introduce a fluorescent tryptophan analog with enhanced photostability and altered electronic properties. The Fmoc group allows for solid-phase synthesis, while the 7-aza substitution increases resistance to oxidation and improves spectral characteristics for fluorescence-based studies. Commonly applied in the development of bioactive peptides, probes for protein-protein interactions, and labeled peptides for imaging or detection in biological systems. Its DL configuration permits incorporation into both natural and modified peptide frameworks, offering flexibility in design for structure-activity relationship studies.