The general procedure for the synthesis of tert-butyl 6-hydrazinonicotinate from tert-butyl 6-chloronicotinate was as follows: first, 18.0 g (84.2 mmol) of tert-butyl 6-chloro-pyridine-3-carboxylate was dissolved in 85 mL of ethanol. Subsequently, 42.2 g (842.0 mmol) of hydrazine hydrate was added to the solution and the reaction mixture was stirred and reacted at 100 °C for 2 hours. Upon completion of the reaction, the mixture was concentrated to remove the solvent. The concentrated residue was dissolved in a solvent mixture of ethyl acetate and water for phase separation. The organic phase was washed sequentially with water and saturated sodium chloride solution each, and then dried with magnesium sulfate. The dried organic phase was concentrated again to obtain the crude product. The crude product was ground with petroleum ether, the solid formed was collected by filtration and dried under high vacuum to give 16.4 g (78% yield) of tert-butyl 6-hydrazinonicotinate. The product was analyzed by LC-MS (Method 1) showing Rt = 2.30 min; MS (ESIpos): m/z = 210 [M + H]+; 1H-NMR (400 MHz, DMSO-d6) data were as follows: δ= 8.49 (d, 1H), 8.30 (s, 1H), 7.82 (dd, 1H), 6.70 (d, 1H). 4.35 (s, 2H), 1.50 (s, 9H).
