Fmoc-L-Dap(Pentynoyl)-OH is a click chemistry reagent featuring an alkyne group, which facilitates the introduction of alkyne functionality into peptide sequences through standard Fmoc/tBu procedures. As an amino acid building block, this compound enables copper-catalyzed azide-alkyne cycloaddition (CuAAC) with azide-containing organic molecules or copper-free coupling reactions with tetrazines. The presence of the pentynoyl group allows for versatile applications in peptide synthesis and modification.