Used in solid-phase peptide synthesis as a chiral building block for introducing pentenyl side chains with a terminal alkene. The Fmoc group allows for mild base deprotection, compatible with standard peptide synthesis protocols. The terminal alkene in the pentenyl side chain serves as a handle for post-assembly modifications, such as cross-metathesis or thiol-ene reactions, enabling peptide functionalization or conjugation to surfaces, tags, or other biomolecules. Its (R)-configuration supports studies on stereochemical effects in peptide structure and activity. Commonly applied in the development of bioconjugates, cyclic peptides, and peptide-based materials.