5-(9-Isobutyl-6-morpholin-4-yl-8-piperazin-1-yl-9H-purin-2-yl)pyrimidin-2-amine (150 mg, 0.33 mmol), 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (128 mg, 0.67 mmol), 1-hydroxybenzotriazole (45 mg, 0.33 mmol), and (S)-3-hydroxybutyric acid (70 mg, 0.67 mmol) were dissolved in dimethylformamide (5 ml) and the resulting mixture was stirred for 16 hours. The solvent was evaporated under reduced pressure and then the residue was purified by preparative HPLC (column, NOMURA Develosil Combi-RP-5; mobile phase, acetonitrile/water/formic acid) to give the title compound (97 mg, 56%) as a white solid.
