LHMDS (1 M tetrahydrofuran solution, 17.11 mL, 17.11 mmol) was dissolved in tetrahydrofuran (5 mL) at -5 °C and tetrahydrofuran solution (5 mL) of 4-chloropyridin-2-amine (1 g, 7.78 mmol) was slowly added and stirred for 5 min. Subsequently, tetrahydrofuran solution (5 mL) of di-tert-butyl dicarbonate (Boc2O, 1.898 mL, 8.18 mmol) was added to the reaction mixture. The reaction system was maintained at 0°C and stirring was continued for 2 h. Upon completion of the reaction, the reaction was quenched by the addition of aqueous ammonium chloride solution. The pH of the reaction solution was adjusted to 6 with 1.5 N hydrochloric acid, followed by extraction with ethyl acetate (3 x 15 mL). The organic phases were combined and washed sequentially with sodium bicarbonate solution (15 mL), water (15 mL) and brine (15 mL). The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (gradient elution with ethyl acetate/petroleum ether) to afford the target product tert-butyl (4-chloropyridin-2-yl)carbamate (1.435 g, 6.28 mmol, 81% yield). The product was characterized by 1H NMR (400 MHz, DMSO-d6): δ 10.10 (s, 1H), 8.23 (d, J = 5.20 Hz, 1H), 7.88 (d, J = 2.00 Hz, 1H), 7.15 (dd, J = 2.00, 5.20 Hz, 1H), 1.48 (s, 9H).
