Scheme 9. Synthesis of the AviCys-Containing Ring of Cypemycin via Condensation of Aldehyde 46 with Amide (Tcp)Val-NH₂, Followed by Elongation of the Peptide Chain and Lactamization to Give 50 in 4.6% Yield from 46(12) (Tcp = 3,4,5,6-Tetrachlorophthalimide, Pht = Phthalimide).