Preparation of the tripeptide fragment (116). a
aReagents and conditions: (a) CuCN (0.9 equiv), LiCl (1.8 equiv), Zn (3.6 equiv), TMSCl (0.1 equiv), Br(CH2)2Br (0.2 equiv), DMF, −20 → 23 °C, 11 h, 60%; (b) LiOH (1.2 equiv), THF/H2O 1:1, 0 °C, 0.5 h; H2N-Ala-Leu-OBn (1.1 equiv), EDC (1.2 equiv), HOBt (1.4 equiv), THF, 0 → 23 °C, 10 h, 97% (two steps).