Two birds with one stone! An intramolecular traceless Staudinger ligation was employed to synthesize cyclic peptides. The final amide bond formation was induced by deprotection of the azidopeptide phosphinothioesters. Treatment with trifluoroacetic acid (TFA) results in the simultaneous removal of the borane along with the protecting groups on the peptide side chains, and chemoselective amide bond cyclization ensues.
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Kleineweischede et al. (2008) studied this question.