General procedure for the synthesis of 1-iodo-5-isopropyl-2,4-dimethoxybenzene from 1-bromo-5-isopropyl-2,4-dimethoxybenzene: 1-bromo-5-isopropyl-2,4-dimethoxybenzene (0.396 g, 1.53 mmol) was dissolved in anhydrous diethyl ether (3 mL) and the solution was cooled to -78 °C. Under stirring, tert-butyl lithium (t-BuLi, 1 mL, 1.7 M in pentane) was added dropwise and the reaction mixture was kept stirring at -78 °C for 45 min. Subsequently, a solution of iodine (I2, 0.391 g, 1.54 mmol) in ether (3 mL) was added all at once, and the reaction was continued at -78 °C for 1 h. The reaction was then slowly warmed to room temperature. Upon completion of the reaction, the reaction mixture was washed with 25% sodium thiosulfate (Na2S2O3) solution to quench the excess iodine. The organic phase was separated, dried over anhydrous magnesium sulfate (MgSO4), filtered and concentrated under reduced pressure. The residue was purified by column chromatography using 10% ethyl acetate (EtOAc)/heptane as eluent to afford 1-iodo-5-isopropyl-2,4-dimethoxybenzene (0.249 g, 53% yield) as a white solid. Nuclear magnetic resonance hydrogen spectrum (1H NMR, DMSO-d6): δ 7.41 (s, 1H), 6.64 (s, 1H), 3.76 (s, 3H), 3.72 (s, 3H), 3.10 (m, 1H), 1.11 (d, 6H).
