One-Pot Ligation–Oxidative Deselenization at Selenocysteine and Selenocystine

The use of native chemical ligation at selenocysteine (Sec) residues with peptide thioesters and additive-free selenocystine ligation with peptides bearing phenyl selenoesters, in concert with one-pot oxidative deselenization chemistry, is described. These approaches provide a simple and rapid method for accessing native peptides with serine in place of Sec at the ligation junction. The efficiency of both variants of the one-pot ligation–oxidative deselenization chemistry is probed through the synthesis of a MUC5AC-derived glycopeptide.