Used in solid-phase peptide synthesis as a protected amino acid derivative, enabling selective coupling and chain elongation in the production of complex peptides. The Fmoc group allows for mild base-labile protection, while the diethylguanidino moiety can serve as a protected form of a positively charged side chain, useful in synthesizing arginine-containing peptides. Its hydrochloride salt form enhances stability and solubility during handling. Commonly applied in research settings for developing therapeutic peptides, biochemical probes, and studying structure-activity relationships in proteins.