General procedure for the synthesis of 3-bromo-2-hydroxybenzonitrile from 2-(benzyloxy)-3-bromobenzonitrile: 2-(benzyloxy)-3-bromobenzonitrile (16.37 g) was dissolved in anhydrous dichloromethane (75 mL), and cooled to -78 °C. A dichloromethane solution of 1 M sodium borohydride (182 mL) was slowly added with stirring. Upon completion of the reaction, the reaction mixture was carefully poured into a pre-cooled ethyl acetate/ice mixture. The organic layer was separated, washed with brine (100 mL), dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The resulting residue was purified by fast column chromatography (FCC) to afford 3-bromo-2-hydroxybenzonitrile (9.12 g, 79% yield). Mass spectrum (ES) m/e 198 [H]+. 1H-NMR (400 MHz, CDCl3) δ: 7.64 (d, J = 2.37 Hz, 1H), 7.59 (dd, J = 2.2.6, 44 Hz, 1H), 6.92 (d, J = 9.2 Hz, 1H), 6.00 (brs, 1H).
