反应详情

温度

-70 °C

A solution of 2-chloro-5-iodo-1,3-dimethoxybenzene (1) (3.4 g, 11 mmol) in anhydrous THF (100 mL) was cooled to −70° C. and treated with n-butyllithium (5.5 mL, 12 mmol). The reaction mixture was stirred at −70° C. for 45 min then ethyl chloroformate (1.6 mL, 17 mmol) was added dropwise and the reaction mixture was allowed to warm to RT and stirred for 20 h. The reaction mixture was poured on to ice (100 mL) and the product was extracted with EtOAc (2×100 mL). The organic solution was washed with brine (3×100 mL) and the solvent was removed in vacuo. The residue was purified by silica gel chromatography (120 g, 0-50% EtOAc in isohexane) to afford ethyl 4-chloro-3,5-dimethoxybenzoate (2) (0.12 g, 4%): 1H NMR (400 MHz, CDCl3) δ: 7.30 (2H, s), 4.40 (2H, q), 3.96 (6H, s), 1.42 (3H, t).

1. temperatureto warm to RT
2. stirringstirred for 20 h
3. extractionthe product was extracted with EtOAc (2×100 mL)
4. washThe organic solution was washed with brine (3×100 mL)
5. customthe solvent was removed in vacuo
6. customThe residue was purified by silica gel chromatography (120 g, 0-50% EtOAc in isohexane)