[CH3:1][N:2]1[C:11](=[O:12])[C:10]2[N:9]([CH2:13][CH2:14][CH2:15][CH2:16][CH2:17][CH2:18]Br)[CH:8]=[N:7][C:6]=2[N:5]([CH3:20])[C:3]1=[O:4].C([O-])(=[O:23])C.[K+].N1C(=O)C2NC=NC=2NC1=O.[I-].[K+]>C(OC(=O)C)(=O)C.C(O)(=O)C>[CH3:1][N:2]1[C:11](=[O:12])[C:10]2[N:9]([CH2:13][CH2:14][CH2:15][CH2:16][CH2:17][CH2:18][OH:23])[CH:8]=[N:7][C:6]=2[N:5]([CH3:20])[C:3]1=[O:4]
1,3-dimethyl-7-(6-bromohexyl)-xanthine is refluxed overnight with a sixfold molar excess of potassium acetate with the addition of catalytic quantities, such as 2 mol percent, referred to the xanthine, of potassium iodide in a mixture of 5 ml of acetic anhydride and 200 ml of glacial acetic acid. The solvent is evaporated in vacuo. The residue is dissolved in water and the pH of the solution is adjusted to a value of 7 with 4N sodium hydroxide. The solution is then extracted with chloroform. The isolated 1,3-dimethyl-7-(acetoxyhexyl)-xanthine is subsequently hydrolysed to the corresponding hydroxyalkyl compound by boiling with 5% sulfuric acid.
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