The mixture of camptothecin (10 mg, 0.029 mmol), 3,4-methylenedioxyphenoxyacetic acid (8 mg, 0.042 mmol), EDCI (28 mg, 0.15 mmol), DMAP (2 mg, 0.02 mmol) and dichloromethane (3 ml) was stirred in the room temperature for 20 h, then dichloromethane (20 ml) was added to the solution. Organic layer was washed with water (20 ml), saturated NaHCO3 aqueous solution (10 ml) and brine (20 ml), and then dried over MgSO4. After the solvent was removed under reduced pressure, the resulting solid was separated by column chromatography (eluent: CHCl3:CH3OH 9:1) to afford 8 mg camptothecin-20-O-3,4-methylenedioxyphenoxyacetate, yield: 53.0%, mp.
