Camptothecin (100 mg, 0.287 m-mol) was suspended in methanol (25 ml) and then dissolved therein by addition under ice-cooling of 75% sulfuric acid (10 ml). To the solution was added dropwise under reflux with stirring an aqueous solution (100 ml) of ammonium persulfate (15 g, 0.0657 mol) over 16 hours. The reaction mixture was poured into ice water (100 ml) and the organic matter was extracted with a mixture (1:1, 500 ml) of dioxane-chloroform and then thrice with chloroform (100 ml×3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered and then evaporated until dryness under reduced pressure. The remaining solid having an orange color was warmed (50°-60° C.) with methanol (200 ml) and stirred for 30 minutes. An insoluble matter was collected by filtration, dried under reduced pressure and recrystallized from dimethylformamide-dioxane whereupon 40 mg (36.9%) of 7-hydroxymethylcamptothecin were obtained as light yellow white prismatic crystals having a melting point of 274°- 276° C. (dec.). Rf value 0.125 (5% methanol-chloroform).
