Fmoc-L-Asn(EDA-N3)-OH is a chemical compound equipped with an azide group used in click chemistry. Reports in the literature have demonstrated its application in the modification of α-amanitin, the deadliest member of the amatoxin peptide family produced by the death cap mushroom. α-Amanitin is a highly lethal natural compound (LD50=50-100 µg/kg), an orally ingested rigid bicyclic octapeptide, acting as a highly selective conformational inhibitor of RNA polymerase II.