62 mg (0.2 mmol) of 6-(4-amino-phenyl-amino)-9-ethyl-2-(2-hydroxy-ethyl-amino)-9H-purine (prepared according to Example 108), 0.18 g (0.4 mmol) of (benzotriazol-1-yloxy)-tris-(dimethylamino)-phosphonium hexafluorophosphate (BOP), 54 mg (0.4 mmol) of 1-hydroxybenzotriazole (HOBT) and 68 μl of diisopropylamine are stirred in 6 ml of dimethylacetamide at RT for 5 min and then treated with 63 mg (0.4 mmol) of 3-chlorobenzoic acid. After the reaction mixture has been stirred at RT for 30 min, it is diluted with ethyl acetate and washed with water. The crude product is purified by chromatography over silica gel (mobile phase: methylene chloride:methanol=9:1). 6-(4-[3-Chloro-benzoyl-amino]-phenyl-amino)-9-ethyl-2-(2-hydroxy-ethyl-amino)-9H-purine is obtained; FAB-MS: (M+H)+=452; Rf=0.45 (methylene chloride:methanol=9:1).
