Peptide-EBX (0.01 mmol) were weighed on the analytical balance and dissolved in 830 μL non-degassed DMA in a 2 mL vial. Afterwards, 120 μL of CzIPN solution (3 µmol, 0.3 equiv.) (25 mM in DMA), 50 μL 2 M K2HPO4 (0.10 mmol, 10 equiv.) in milli-Q purified water were added (concentration: 10 mM). The vial was then capped and degassed by bubbling with N2 for 20 min. The reaction was stirring under Blue LEDs irradiation for 30 min at RT. The cyclic peptides were isolated by Prep-RP-HPLC, followed by lyophilization.