General procedure for the synthesis of 4-amino-3-nitrobenzaldehyde from 4-fluoro-3-nitrobenzaldehyde: To a solution of 4-fluoro-3-nitrobenzaldehyde (570 mg, 3.3 mmol) in tetrahydrofuran (THF, 20 mL) was added ammonia (NH4OH, 5 mL). The reaction mixture was stirred at room temperature for 1 hour. Upon completion of the reaction, the resulting yellow solid was collected by filtration and washed with distilled water. Subsequently, the solid was dried under vacuum to afford the target compound 4-amino-3-nitrobenzaldehyde (300 mg, yield: 53%). The structure of the product was confirmed by 1H-NMR (300 MHz, DMSO-d6) with the following chemical shifts: δ 9.76 (s, 1H), 8.57 (d, 1H), 8.18 (br s, 2H), 7.80 (dd, 1H), 7.10 (d, 1H).
