General procedure for the synthesis of 1,4-diiodo-2,5-dimethoxybenzene from 1,4-dimethoxybenzene: 1,4-dimethoxybenzene (2.70 g, 20.0 mmol) was dissolved in methanol (25 mL) and stirred for 10 min according to Ko et al. Iodine (6.38 g, 25.0 mmol) was subsequently added to the mixture. The reaction mixture was heated at 70°C for 4 hours. Upon completion of the reaction, the mixture was poured into a solution of water (50 mL) containing sodium thiosulfate (5.00 g, 31.6 mmol). The resulting solution was filtered and the precipitate was washed with methanol (20 mL) and then dissolved in dichloromethane (20 mL). After filtration through a sintered funnel, the filtrate was evaporated in vacuum to afford the target product 1,4-diiodo-2,5-dimethoxybenzene as a white solid (7.52 g, 97% yield).1H NMR (400 MHz; CDCl3) δ 3.82 (6H, s, OCH3), 7.19 (2H, s, Ar-H).The 1H NMR data were in agreement with the literature values.
