Traceless chemical ligations from O-acyl serine sitesElectronic supplementary information (ESI) available: 1H and 13C NMR for all compounds and HPLC/Mass-Spectrometry spectra for compounds 4, 5, 7 and 8. See DOI: 10.1039/c2ob07050b

Chemical ligation via O - to N -acyl transfer of O -acylated serine containing peptides affords serine containing native peptides via 8- and 11-membered cyclic transition states opening the door to a wide variety of potential applications to peptide elaboration. The feasibility of these traceless chemical ligations is feasible as supported by computation. The feasibility of these traceless chemical ligations is demonstrated experimentally and as supported by computation.