(R)-3-hydroxybutanoic acid (39 mg, 0.38 mmol), hydroxybenzotriazole hydrate (58 mg, 0.38 mmol), 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (72 mg, 0.38 mmol), dimethylformamide (5 ml), triethylamine (161 μl) were added to 5-[6-morpholin-4-yl-8-piperazin-1-yl-9-(2,2,2-trifluoroethyl)-9H-purin-2-yl]pyrimidin-2-amine trifluoroacetate (200 mg, 0.29 mmol) and the resulting mixture was stirred for 15 hours. The reaction mixture was partitioned with ethyl acetate and saturated aqueous sodium bicarbonate solution, the organic layer was dried over magnesium sulfate, and then the solvent was evaporated under reduced pressure. The residue was purified by silica gel chromatography (chloroform:methanol=19:1) to give the title compound (77 mg, 48%) as a colorless solid.
