At room temperature, N-hydroxyacetamide (3.1 g, 41 mmol) was dissolved in anhydrous N,N-dimethylformamide (60 mL), followed by the addition of potassium tert-butoxide (4.6 g, 41 mmol). The reaction mixture was stirred for 30 minutes, then 4-chloro-2-nitrobenzonitrile (5.0 g, 27 mmol) was added and the reaction was continued with stirring for 4.5 hours. Upon completion of the reaction, the mixture was poured into a pre-prepared mixture of brine (60 mL) and ethyl acetate (60 mL). The organic phase was separated, dried over anhydrous sodium sulfate, filtered and concentrated to dryness. The residue was purified by silica gel column chromatography with the eluent ratio of petroleum ether:ethyl acetate=3:1 to afford the target compound 6-chloro-3-aminobenzisoxazole (B-1, 3.1 g, 66% yield) as a light yellow solid.1H-NMR (DMSO-d6, 400 MHz) δ:7.84-7.82 (d,J=8.8 Hz, 1H),7.65- 7.64 (d,J=1.2Hz,1H),7.33-7.31 (dd,J=1.2Hz,J=8.8Hz,1H),6.52 (s,2H).
