To a stirred solution of methyl 1-(7-(3,4-dimethoxyphenylamino)thiazolo[5,4-d]pyrimidin-5-yl)piperidine-3-carboxylate (0.06 g, 0.139 mmol) in 5 mL of THF and 5 mL of methanol was added a solution of NaOH (0.056 g, 1.39 mmol) in 1 mL of water at room temperature. After the addition, the reaction was stirred at this temperature for 24 hours. The solvent was evaporated and the residue was suspended in 10 mL of THF, then treated by HCl until pH=2. The solvent was evaporated and then dissolved in 30 mL of THF, filtered. The filtrate was evaporated to give 1-(7-(3,4-dimethoxyphenylamino)thiazolo[5,4-d]pyrimidin-5-yl)piperidine-3-carboxylic acid (0.057 g, 98%) as a solid. LC-MS: 416.1 [M+H]+, tR=1.57 min.
