General procedure for the synthesis of 3-bromo-4-chlorobenzyl alcohol from 3-bromo-4-chlorobenzoic acid:
A. To a mixture of 3-bromo-4-chlorobenzoic acid (10.0 g, 42.5 mmol) in THF (50 mL) was slowly added 1.0 M borane-THF solution (55.3 mL, 55.3 mmol) under nitrogen protection and at 0 °C. The reaction mixture was stirred overnight at room temperature and then carefully poured into a mixture of NaHCO3/H2O/ice and extracted with EtOAc. The organic layer was washed with saturated aqueous NaCl, dried over MgSO4, filtered and concentrated under reduced pressure to afford the target product 3-bromo-4-chlorobenzyl alcohol (9.4 g, 100%) as a clear, colorless oil.1H NMR (300 MHz, CDCl3) δ 7.61 (s, 1H), 7.41 (d, J = 5.1 Hz, 1H), 7.21 (d, J = 5.1 Hz, 1H), 4.63 (s, 2H), 2.12 (br s, 1H).
