To a dry 50 mL three-necked flask was added 2-amino-5-bromo-6-fluoropyridine (370 mg, 1.93 mmol), potassium acetate (569 mg, 5.8 mmol), pinacol ester of bis(boronic acid) (538 mg, 2.12 mmol) and dioxane (15 mL). After bubbling through argon for 15 minutes, 1,1'-bis(diphenylphosphino)ferrocene palladium(II) chloride dichloromethane adduct (79 mg, 0.09 mmol) was added. The reaction mixture was refluxed in an oil bath at 115 °C for 4 h under argon protection. After completion of the reaction, the solvent was removed by distillation under reduced pressure and ethyl acetate (150 mL) was added to dissolve the residue. The organic phase was washed sequentially with water (3 x 40 mL) and saturated sodium chloride solution (300 mL), dried over anhydrous sodium sulfate, filtered and concentrated. Purification by silica gel column chromatography (eluent: 30% ethyl acetate/hexane) afforded the target product 2-fluoro-6-amino-5-pyridineboronic acid ester (161 mg, 35% yield).LC-MS (m/z): 157 ([M+H]+ of boronic acid from in situ hydrolysis product in liquid chromatography).1H NMR (CDCl3): δ 7.86 (t, J = 8.4 Hz, 1H), 6.29 (dd, J = 8.1, 2.7 Hz, 1H), 4.70 (br s, 2H), 1.32 (s, 12H).
