Used in solid-phase peptide synthesis as a chiral building block for introducing a side chain with a terminal alkene functionality. The Fmoc group allows for mild base-labile protection during stepwise synthesis, enabling the construction of complex peptides with site-specific modifications. The pentenyl side chain serves as a handle for post-assembly functionalization, such as thiol-ene coupling or ring-closing metathesis, useful in peptide cyclization or conjugation to carriers, surfaces, or labels. Particularly valuable in developing peptide-based therapeutics, probes, and biomaterials where precise control over structure and functionalization is required.