Ammonium Chloride → 3-Amino-5-bromo-4-chlorobenzonitrile

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(I1D): A mixture of 3-bromo-4-chloro-5-nitrobenzonitrile (0.99 g, 3.79 mmol), iron (1.057 g, 18.93 mmol) and ammonium chloride (2.025 g, 37.9 mmol) in THF, MeOH and water (60 ml, 1:1:1) was heated to reflux for 1 h. More iron (0.5 g) and NH4Cl (2 g) added, heated for another 2 h and then cooled to room temperature. Filtered off solid, the filtrate was concentrated to remove the organic solvent. The residue was diluted with water, extracted with EtOAc twice, dried and concentrated to dryness. The resulting solid was trituard with EtOAc, solid was filtered off through celite pad and the filtrate was concentrated to give 0.88 g of 3-amino-5-bromo-4-chlorobenzonitrile as yellow solid which was used as such in the next reaction. Intermediate 1: To a solution of 3-amino-5-bromo-4-chlorobenzonitrile (0.88 g, 3.80 mmol) in DCM (25 mL) was added TEA (1.590 mL, 11.41 mmol), BOC2O (1.059 mL, 4.56 mmol) and DMAP (0.464 g, 3.80 mmol). The mixture was stirred at room temperature for 16 h. The reaction mixture was concentrated, the crude product was purified using ISCO silica gel column (24 g, EtOAc/hexane=0-30%) to give 0.667 g of tert-butyl 3-bromo-2-chloro-5-cyanophenylcarbamate as white solid

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