Chemoselective fragment condensation between peptide and peptidomimetic oligomers.

We report the first example of chemoselective fragment condensation, through native amide bond formation, between peptoid and peptide oligomers. Peptoid oligomers bearing C-terminal salicylaldehyde esters were synthesized and ligated to peptides containing N-terminal serine or threonine residues. We investigate the ligation efficiency of peptoid oligomers varying in length, sequence, and C-terminal steric bulk. These protocols enhance accessibility of structurally complex peptoid-peptide hybrids and will facilitate the design new semi-synthetic proteins with unique attributes.