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General procedure for the synthesis of isoxazolo[5,4-c]pyridin-3-amines from acetohydroxamic acid and 3-chloro-4-cyanopyridine: Intermediate 1: Synthesis of isoxazolo[5,4-c]pyridin-3-amines. To a solution of N,N-dimethylformamide (DMF, 6.0 mL) of 3-chloro-4-cyanopyridine (1.13 g, 8.36 mmol) was sequentially added potassium carbonate (1.69 g, 12.2 mmol) and acetohydroxamic acid (0.91 g, 12.2 mmol). The reaction mixture was stirred at room temperature overnight, and when the reaction was complete, it was diluted with ethyl acetate (EtOAc, 200 mL) and washed sequentially with saturated aqueous sodium bicarbonate (200 mL) and saturated aqueous sodium chloride (100 mL). The aqueous layer was back-extracted with ethyl acetate (200 mL), and the organic layers were combined, dried with anhydrous magnesium sulfate (MgSO?), and concentrated under reduced pressure. The crude product was purified by fast column chromatography (FCC, eluent: methanol/dichloromethane solution containing 2N ammonia) to give isoxazolo[5,4-c]pyridin-3-amine (0.447 g, 41% yield). Mass spectrum (ESI+): m/z of C?H?N?O was calculated as 135.04 and measured as 136.2 ([M+H]+). 1H NMR (d6-DMSO): δ 8.93 (d, J = 0.8 Hz, 1H), 8.45 (d, J = 5.2 Hz, 1H), 7.88-7.86 (dd, J = 5.2, 1.2 Hz, 1H), 6.72 (br s, 2H).