Scheme 3. Synthetic route of combretastatin sulfamide derivatives. Reagents and conditions: a) n-BuLi, THF, −78 °C, 30 min, then adding 13e/THF solution, −78 °C–rt, overnight; b) Zn, CH₃COOH, 2 h, rt; c) NaH, DMF, NH₂SO₂Cl, 0 °C–rt, overnight; d) H₂ (1 atm), 10% Pd/C, EtOH, rt, 3 h.