Synthesis of asparagusic acid modified lysine and its application in solid-phase synthesis of peptides with enhanced cellular uptake

Cyclic disulfides, such as asparagusic acid, enhance the uptake of a variety of cargoes into live cells. Here, we report a robust and scalable synthesis of an asparagusic acid modified lysine. This amino acid can be used in solid-phase peptide synthesis. We confirmed that incorporation of this building block into the sequence of a peptide increases its cellular uptake substantially.