1: 98 percent / (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate, DIEA 2: 93 percent / LiOH 3: 62 percent / DIAD, PPh3, TsOH*H2O / tetrahydrofuran / 2 h / 0 °C 4: 84 percent / I2 / methanol; H2O View Scheme