Stannous Chloride → (2-Bromo-5-nitrophenyl)hydrazine

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To a suspension of 2-bromo-5-nitroaniline (1 g, 4.6 mmol) in conc. HCl (10 mL) at 0° C. was slowly added a solution of NaNO2 (382 mg, 5.5 mmol) in water (1.5 mL). Then, the mixture was stirred at 0° C. for 3 hr until TLC and LCMS analysis showed that most of 2-bromo-5-nitroaniline was consumed. SnCl2 (1.90 g, 10 mmol) in conc. HCl (3 mL) was slowly added. The mixture was then stirred at RT for 2 hr before re-cooled to 0° C. Then, the PH was adjusted with sat. aq. NaHCO3 to 7-8. The mixture was extracted with ethyl acetate (3×50 mL). The combined organic layers were washed with brine, dried over Na2SO4, filtered and concentrated to get crude product which was further chromatographed on 10 g of silica gel using PE/EA (20/1 to 4/1) as eluant to afford 560 mg (51%) of (2-bromo-5-nitrophenyl)hydrazine as a orange solid. 1H NMR (400 MHz, DMSO-d6) δ 7.89 (d, J=2.8 Hz, 1H), 7.60 (d, J=8.6 Hz, 1H), 7.29 (dd, J=2.8, 8.6 Hz, 1H), 7.04 (s, 1H), 4.38 (s, 2H). MS (ESI) m/e [M+1]+ 232, 234.

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