Efficient loading of sulfonamide safety-catch linkers by Fmoc amino acid fluorides

[reaction: see text] Fmoc-protected amino acid fluorides were found to be excellent reagents for the acylation of sulfonamide safety-catch linkers (SCL) suitable for the subsequent preparation of peptide C-terminal thioesters. High loadings were obtained on different types of resins with low levels of epimerization.