Camptothecin (3.00 g, 8.61 m-mol) was suspended in methanol (90 ml) and then dissolved therein by addition of 75% sulfuric acid (75 ml) and 75 ml of water. To the solution was added FeSO4. 7H2O (40 g, 0.143 mol) and then was added dropwise under ice-cooling and agitation 30% hydrogen peroxide (15 ml) over 2 hours. After addition of the hydrogen peroxide, the reaction mixture was stirred for 14 hours at room temperature and poured into ice water (1 l). The yellowish brown solid precipitated was collected by filtration and dried under reduced pressure whereby 2.5 g of 7-hydroxymethylcamptothecin were obtained. The filtrate was extracted with chloroform (250 ml×4) thereby obtaining 200 mg of crude crystals of the product. 2.7 Grams (82.9%) in toto of 7-hydroxymethylcamptothecin were obtained, which was identified to be the same product as obtained in Example 1 by way of IR-absorption spectra and thin layer chromatography.
