Access to Cyclic or Branched Peptides Using Bis(2-sulfanylethyl)amido Side-Chain Derivatives of Asp and Glu

Bis(2-sulfanylethyl)amido (SEA) side-chain derivatives of aspartic and glutamic acids enable the synthesis of tail-to-side chain cyclic or branched peptides using standard Fmoc-SPPS followed by SEA native peptide ligation.