4-Toluenesulfonyl chloride → 2-(5-Bromo-7-chlorobenzofuran-2-yl)ethyl 4-methylbenzenesulfonate

関与物質

反応手順

To a solution of the product of step B (3.5 g, 12.7 mmol) in dichloromethane (30 mL) was added triethylamine (3.7 mL, 25.4 mmol) followed by p-toluenesulfonyl chloride (3.6 mL, 19.05 mmol) at 0° C. The reaction mixture was stirred at ambient temperature for 12 h and concentrated in vacuo. The reaction mixture was quenched with saturated sodium bicarbonate solution, washed with 0.5 N HCl and extracted with ethyl acetate (2×20 mL). The combined organic extracts were dried over Na2SO4 and concentrated in vacuo to give the crude product which was purified by column chromatography (SiO2, 4:1 hexanes/ethyl acetate) providing 2-(5-bromo-7-chlorobenzofuran-2-yl)ethyl 4-methylbenzenesulfonate (5.1 g, 95%) as an off-white solid: 1H NMR (CDCl3, 400 MHz) δ 7.66-7.62 (m, 2H), 7.49 (d, J=2.0 Hz, 1H), 7.36 (d, J=1.6 Hz, 1H), 7.18-7.14 (m, 2H), 6.43 (s, 1H), 4.39 (t, J=6.4 Hz, 2H), 3.14 (t, J=6.0 Hz, 2H), 2.37 (s, 3H).

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