General procedure for the synthesis of 2-bromo-6-hydrazinopyridine from 2,6-dibromopyridine: commercially available 2,6-dibromopyridine (4.12 g, 16.6 mmol) was suspended in ethanol (40 mL), followed by the addition of hydrazine hydrate (10 mL, 97.6 mmol, 50-60% aqueous solution). The reaction mixture was heated and refluxed in a sand bath at 115°C for 18 hours. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure and the resulting residue was purified by silica gel column chromatography with the eluent ethyl acetate/n-heptane (60/40, v/v) to afford 2-bromo-6-hydrazinopyridine as an off-white solid (3.05 g, 93% yield).1H-NMR (400 MHz, CDCl3) δ: 7.33 (t, 1H), 6.83 (d, 1H ), 6.67 (d, 1H), 6.00 (br-s, 1H), 3.00-3.33 (br-s, 2H).
