A mixture of 1-{2-[4-(4-Chloro-2-fluoro-5-methoxy-phenyl)-2-(S)-methyl-piperazin-1-yl]-2-oxo-ethyl}-1H-pyrazolo[3,4-b]pyridine-3-carbonitrile (1.6 g, 3.6 Mmol, 1 eq), NH2OH.HCl (0.84 g, 10.8 mmol, 3 eq), TEA (1.5 mL), and ethanol (10 mL) was stirred at 65° C. overnight. The reaction solution was concentrated in vacuo, and dissolved in ethyl acetate, washed with brine, and concentrated to provide 1-{2-[4-(4-Chloro-2-fluoro-5-methoxy-phenyl)-2-methyl-piperazin-1-yl]-2-oxo-ethyl}-N-hydroxy-1H-pyrazolo[3,4-b]pyridine-3-carboxamidine (1.2 g).
