Fig. 6 in A comprehensive review: Biological activity, modification and synthetic methodologies of prenylated flavonoids

Fig. 6. Synthesis of potential MDR reversal icariin derivatives (231–236). Reagents and conditions: (a) H2SO4 (2–5 equiv), 90% EtOH, reflux; 1.5 h; (b) 20% H2SO4, MeOH, reflux, 2 h; (c) 20% H SO, MeOH, 25 ◦ C, 4 h; (d) ClSO CH, Et N, 4 h, then HCl; (e) ClSO CH, pyridine, 0 ◦ C, 3 h; then HCl; (f) ClSO NH, DMA, CH Cl, 2 4 2 3 3 2 3 2 2 2 2 0 ◦ C, 3 h; (g) ClSO H, Et N, 0 ◦ C, 3 h; then HCl.