Scheme 4. Synthesis of FMK-peptides 13–16. Reagents and conditions: (i) NaOAc, EtOH, H₂O, reflux; (ii) HATU, DMF, DIPEA; (iii) non-automated SPPS using Fmoc aa, HATU, DIPEA, DMF; (iv) 95% TFA, 2.5% H₂O, 2.5% TIPS; (v) fully automated SPPS using Fmoc aa, HATU, DIPEA, DMF.