The general procedure for the synthesis of 2-(trifluoromethoxy)phenylboronic acid from 1-bromo-2-(trifluoromethoxy)benzene was as follows: n-butyllithium (5.9 mL, 9.5 mmol) was slowly added dropwise to a solution of 1-bromo-2-(trifluoromethoxy)benzene (2 g, 8.2 mmol) in tetrahydrofuran (28 mL) at -78 °C and the reaction was stirred for 45 min. Subsequently, triisopropyl borate (2.58 mL, 11.1 mmol) was slowly added dropwise to the reaction mixture and the reaction system was slowly warmed to room temperature over 16 hours. Upon completion of the reaction, the reaction was quenched with water, the pH was adjusted to alkaline with 2 N NaOH solution and subsequently extracted with ethyl acetate. The aqueous phase was acidified to pH acidic with 2 N HCl solution, stirred for 1 h at room temperature and again extracted with ethyl acetate. The organic phases were combined, washed sequentially with water and saturated saline and dried over anhydrous sodium sulfate. After filtration, the organic phase was concentrated under reduced pressure to afford the target product 2-(trifluoromethoxy)phenylboronic acid (1.10 g, 65% yield) as a white solid. The product was confirmed by NMR hydrogen spectroscopy (CDCl3): δ 7.96 (dd, J = 7.2, 1.6 Hz, 1H), 7.53 (ddd, J = 9.1, 7.3, 1.8 Hz, 1H), 7.38 (td, J = 7.3, 0.7 Hz, 1H), 7.28 (d, J = 8.2 Hz, 1H), 5.25 (br s, 2H). Mass spectrometry analysis showed the molecular ion peak m/e 206.9 (M + 1)+.
