At -78 °C, n-butyllithium (n-BuLi, 1.67 M hexane solution, 1.32 mL, 2.2 mmol) was slowly added dropwise to a tetrahydrofuran (THF, 3 mL) solution of 2,6-dibromopyridine (383 mg, 2.0 mmol) and the dropwise process was continued for 30 min. Subsequently, ethyl formate (1.6 mL, 20 mmol) was added to the reaction mixture and stirring was continued at -78 °C. After maintaining this temperature for 3 hours, iodine (I2, 1523 mg, 6 mmol), potassium carbonate (K2CO3, 1382 mg, 10 mmol), and ethanol (EtOH, 3 mL) were added sequentially, and then the mixture was warmed to room temperature and stirred for 14 hours. After completion of the reaction, the reaction was quenched with saturated aqueous sodium sulfite (Na2SO3) (5 mL) and extracted with chloroform (CHCl3, 3 x 20 mL). The organic layers were combined, washed with brine, dried over anhydrous sodium sulfate (Na2SO4) and concentrated to give ethyl 6-bromopyridine-2-carboxylate in 77% yield. If necessary, the product could be further purified by silica gel column chromatography (eluent: hexane/ethyl acetate=9:1) to obtain ethyl 6-bromopyridine-2-carboxylate as colorless oil.
