Scheme 1. Synthesis of target allocolchichine derivatives 5, 12. Reagents and conditions: (a) Boc₂O, DMAP, Et₃N, CH₃CN, reflux, 3 h; (b) MeONa, MeOH, 40 °C, 1 h; (c) TFA, CH₂Cl₂, r.t., 1 h; (d) glycolic acid (for compds 3, 8) or N-Boc-glycine (for 4, 9), or appropriate unsaturated acid (for 5a–d, f–j, 12a, b), DIC, NHS, Et₃N, CH₂Cl₂, rt, 16 h; then HCl, CH₂Cl₂, rt, 1 h in case of 4 and 9; 3,3-dimethylacrylic acid, DCC, DMAP, CH₂Cl₂, rt, 16 h for compd 5e; (e) 0.1 M HCl, AcOH, 100 °C, 3 h; (f) NaOH, I₂, KI, H₂O, 0–5 °C, 2 h; (g) MOMCl, DIPEA, CH₂Cl₂, 0–20 °C, 20 h; (h) Boc₂O, DMAP, Et₃N, CH₃CN, reflux, 26 h; (i) NaOMe (20 mol%), MeOH, rt, 1.5 h; (j) HCl, EtOH, rt, 20 h; (k) propargyl acetate (for 10) or propargyl alkohol (for 11), Pd(OAc)₂ (0.05 equiv.), CuI (0.1 equiv.), AcOK (3 equiv.), Ph₃P (0.15 equiv.), CH₃CN, 70 °C, 10 h.