In a round-bottomed flask, 4-{3-[7-tert-butylcarbamoyl-5-(2-trimethylsilanylethoxymethyl)-5H-pyrrolo[2,3-b]pyrazin-2-yl]-5-difluoromethoxy-indazol-1-yl}-butyric acid methyl ester (98 mg, 0.155 mmol) was suspended in THF (1.1 ml), methanol (1.1 ml) and water (1.1 ml). Then, aqueous 1.0 M lithium hydroxide (0.80 ml, 0.80 mmol) was added. The light yellow suspension was stirred at 75° C. for 8 h then cooled to room temperature and stirred overnight. The reaction was diluted with water and acidified with 1 M HCl until pH=˜2 then extracted with dichloromethane (3×). The organic layers were combined, dried over sodium sulfate, filtered and concentrated. The residue was triturated with diethyl ether to afford 81 mg (85%) of 4-{3-[7-tert-butylcarbamoyl-5-(2-trimethylsilanyl-ethoxymethyl)-5H-pyrrolo[2,3-b]pyrazin-2-yl]-5-difluoromethoxy-indazol-1-yl}-butyric acid as a brown powder.
