4-Bromophenol → 4-Bromophenyl dichlorophosphate

Following the procedure described by McGuigan et al.,1993, Supra, a solution of p-bromophenol (13.20 g; 76.30 mmol) and distilled triethylamine (10.65 mL) in anhydrous Et2O (165 mL) was added dropwise into a vigorously stirred solution of phosphoryl chloride (8.5 mL; 91.2 mmol) in anhydrous Et2O (83 mL) at 0° C. over a period of three hours under nitrogen atmosphere. Subsequently, the resultant mixture was gradually warmed up to room temperature, stirred efficiently overnight at room temperature and then heated to reflux for two hours. The reaction mixture was cooled to room temperature and filtered under aspirator pressure. The precipitate was washed with anhydrous Et2O (2×50 mL). The combined Et2O layers were evaporated to dryness on rotary evaporator to yield crude 4c as a pale yellow oil which was then subjected to vacuum distillation to give pure 4c (14.05 g; 63.5% yield) as a colorless viscous oil (bp. 110-115° C./2 mm Hg). IR (Neat) 3095, 1481, 1303, 1187, 948, 829 cm−1. 1H NMR (300 MHz, CDCl3) δ 7.50 (2H, d, J=9.0 Hz), 7.15 (2H, d, J=9.0 Hz). GC/MS (m/e) 290 (M+), 254 (M+−Cl), 173 (M+−POCl2, 81Br), 171 (M+−POCl2, 79Br), 156 (M+−PO2Cl2, 81Br), 154 (M+−PO2Cl2, 79Br).