L-Lactic acid (25.2 μl, 0.29 mmol), 1-hydroxybenzotriazole monohydrate (36.7 mg, 0.24 mmol), 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (68.8 mg, 0.36 mmol), and triethylamine (50.1 μl, 0.36 mmol) were added to an N,N-dimethylformamide suspension (2.0 ml) of 5-[9-(cyclopropylmethyl)-6-morpholin-4-yl-8-piperazin-1-yl-9H-purin-2-yl]pyrimidin-2-amine (104.5 mg, 0.24 mmol) at room temperature. The resulting mixture was stirred for 17 hours and then the reaction mixture was poured into methylene chloride-methanol (10:1), washed with saturated aqueous sodium hydrogencarbonate solution, and dried over anhydrous sodium sulfate. After filtration, the filtrate was concentrated under reduced pressure and the resulting residue was purified by preparative thin layer silica gel chromatography (methylene chloride:methanol=10:1) to give the title compound (80.1 mg, 66%) as a pale yellow solid.
