1402238-32-7

5419-55-6

851199-57-0

1402238-32-7

Step 4: To a 300 mL three-necked round-bottomed flask that was pre-purged and maintained in an inert atmosphere under nitrogen protection was added a tetrahydrofuran solution (50 mL) of 1-(2-fluorophenoxy)-4-iodobenzene (3.3 g, 30.51 mmol, 1.00 equiv). The reaction system was cooled to -78 °C and n-butyllithium (n-BuLi, 4.4 mL) was slowly added dropwise under stirring. After completion of the dropwise addition, the reaction solution was continued to be stirred at -78 °C for 10 min, followed by slow dropwise addition of triisopropyl borate (2.1 g, 13.17 mmol, 1.06 equiv) at the same temperature. After completion of the dropwise addition, the reaction system was gradually warmed up to room temperature and stirred. Upon completion of the reaction, the reaction was quenched by the addition of saturated aqueous ammonium chloride (NH4Cl), followed by concentration of the reaction solution under reduced pressure. The concentrated residue was diluted with 30% aqueous potassium hydroxide (KOH) and then washed with ether. The pH of the aqueous phase was adjusted to 2-4 with 37% hydrochloric acid (HCl) and subsequently extracted with ethyl acetate. The organic layers were combined, dried over anhydrous sodium sulfate (Na2SO4) and concentrated under reduced pressure to give 2.2 g (90% yield) of [4-(2-fluorophenoxy)phenyl]boronic acid as a white solid.