2-Bromo-3-iodopyridine

109-04-6

265981-13-3

a) Under argon protection, n-BuLi (12.78 mL, 2.5 M hexane solution, 31.96 mmol) was slowly added dropwise to a tetrahydrofuran (THF, 100 mL) solution of iPr2NH (4.44 mL, 31.96 mmol), and the reaction system was maintained at -45 °C. After stirring for 0.5 h, the reaction mixture was further cooled to -95 °C (toluene/liquid nitrogen bath), followed by the addition of 2-bromopyridine (3.02 mL, 31.65 mmol). The reaction mixture was stirred at -95 °C to -90 °C for 3 to 4 hours, then iodine (I2, 8.03 g, 31.65 mmol) was added in batches. The reaction mixture was slowly warmed to room temperature and stirred overnight. The reaction was quenched with 10% aqueous acetic acid (HOAc), the pH was adjusted to 8-9 and distilled water (50 mL) was added. The organic phase was extracted with ether and the combined organic phases were dried with anhydrous K2CO3. The solvent was removed by concentration under reduced pressure to give the crude 2-bromo-3-iodopyridine as a brown powder. The crude product was dried with KOH pellets under vacuum for 3 hours. The purity of 2-bromo-3-iodopyridine (7.66 g, 85% yield) was confirmed by 1H NMR analysis and used directly in the next reaction.1H NMR (499.93 MHz, CDCl3, 25 °C): δ = 8.05 (dd, J = 0.6, 5.2 Hz, 1H), 7.91 (dd, J = 0.6, 1.5 Hz, 1H), 7.62 ( dd, J = 1.5, 5.2 Hz, 1H). The data obtained are in agreement with those reported in the literature [17].