Fmoc-Based Synthesis of Peptide Thioesters for Native Chemical Ligation Employing a tert-Butyl Thiol Linker

tert-Butyl thioesters display an astonishing stability toward secondary amines in basic milieu, in contrast to other alkyl and aryl thioesters. Exploiting this enhanced stability, peptide thioesters were synthesized in a direct manner, applying a tert-butyl thiol linker for Fmoc-based solid-phase peptide synthesis.