General procedure for the synthesis of 2,5-difluoro-4-hydrazinylbenzonitrile from 2,4,5-trifluorobenzonitrile: 2,4,5-trifluorobenzonitrile (1 g, 6.3 mmol) was dissolved in hydrazine hydrate (610 mg, 19 mmol) in 1,4-dioxane (3 mL), and the reaction was stirred for 16 hours at room temperature. Upon completion of the reaction, the reaction mixture was extracted by partitioning between ethyl acetate (30 mL) and saturated aqueous sodium bicarbonate (20 mL). The organic layer was separated, washed with saturated aqueous sodium chloride solution (10 mL), dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to afford 4-hydrazino-2,5-difluorobenzonitrile (1.012 g, 93% yield) as a white solid.LC-MS analysis showed m/z (M+H)+ of 170.0.1H-NMR (400 MHz, DMSO-d6) δ (ppm): 4.41 (2H, broad peak), 6.93 (1H, double peak), 7.51 (1H, double peak), 8.22 (1H, broad peak).
