4.2.1. Synthesis of Peptides with Lactam Bridge

Peptides were prepared by standard Fmoc-SPPS as described above, using protected amino acids. Upon completion of the linear peptide synthesis, the Alloc group was removed. PhSiH3 (25 eq.) in 5 mL of CH₂Cl₂ was added to the resin followed by Pd(PPh3)4 (0.25 eq.) in CH₂Cl₂. After 1h resin agitating in the dark, the solution was drained and the reaction was repeated. The resin was washed with 3 volumes of CH₂Cl₂, 4 volumes of 1M pyridine in DMF and 3 volumes of DMF. OxymaPure (3 eq.) and DIC (3 eq.) in 5 mL of DMF were added to the resin and agitated overnight. The resin was washed with 3 volumes of DMF and 3 volumes of CH₂Cl₂. After standard peptide cleavage conditions (described above), the crude peptide was purified by Preparative HPLC and lyophilized.