Camptothecin (50 mg, 0.143 m-mol) was dissolved in 75% sulfuric acid (3 ml). To this solution were added glycolic acid (500 mg, 6.57 m-mol) and silver nitrate (250 mg, 1.31 m-mol) and then was added dropwise under heating (100°-110° C.) and agitation and aqueous solution (15 ml) of ammonium persulfate (3.00 g, 0.0131 m-mol) over 2 hours. After the reaction mixture was allowed to cool, ice water (100 ml) was poured into the reaction mixture which was then extracted with chloroform (100 ml×3). The chloroform layers were combined, washed with a 7% aqueous solution of sodium bicarbonate (300 ml) and then with a saturated edible salt solution (100 ml), dried with anhydrous magnesium sulfate, filtered and evaporated until dryness under reduced pressure. The residue was subjected to thin layer chromatography (5% methanol-chloroform) to effect separation and purification of 7-hydroxymethylcamptothecin whereupon 10.3 mg (19.0%) of pure 7-hydroxymethylcamptothecin were obtained. Besides this, 10.7 mg of camptothecin were recovered.
