The general procedure for the synthesis of 2-iodo-3-bromophenol from 3-bromo-2-iodophenyl diethylcarbamate (3; 3.96 g, 10 mmol) was carried out as follows: to a solution of 3-bromo-2-iodophenyl diethylcarbamate in ethanol (EtOH, 100 mL) was added powdered sodium hydroxide (NaOH, 4.0 g, 100 mmol) in two portions. The reaction mixture was heated to reflux and maintained for 24 hours. The reaction progress was monitored by thin layer chromatography (TLC). After completion of the reaction, the mixture was cooled to room temperature (r.t.) and the reaction was quenched with 2 M aqueous hydrochloric acid (HCl). The aqueous layer was extracted with ethyl acetate (EtOAc, 3 × 30 mL). The organic layers were combined, washed with saturated saline (brine) and dried with anhydrous sodium sulfate (Na2SO4). Subsequently, the solvent was removed by evaporation under reduced pressure. The crude product was purified by silica gel column chromatography using petroleum ether (PE)/ethyl acetate (EtOAc) (8:1) as eluent to afford the target product, 2-iodo-3-bromophenol, as a white solid; Yield: 2.66 g (89% yield); Melting point: 85-87 °C. The spectral data (1H NMR and 13C NMR) of compound 4 were in agreement with literature reports.1H NMR (400 MHz, CDCl3) δ= 7.20 (dd, J = 8.1, 1.5 Hz, 1H), 7.12 (t, J = 8.1 Hz, 1H), 6.92 (dd, J = 8.1, 1.5 Hz, 1H), 5.54 (br s, 1H ). 13C NMR (400 MHz, CDCl3) δ= 156.6, 130.8, 129.6, 125.0, 113.3, 94.4.
