反应详情

Methyl 2-(3,4-dichlorophenyl)-4-hydroxychroman-3-carboxylate (90 mg) and p-toluenesulfonic acid hydrate (24 mg, 128 μmol) were dissolved in toluene (4.0 mL) and heated to reflux. After 40 min, the solution was cooled to rt, diluted with ethyl acetate, washed with saturated aqueous sodium bicarbonate, dried over sodium sulfate and concentrated under vacuum to provide racemic methyl 2-(3,4-dichlorophenyl)-2H-chromene-3-carboxylate as a white solid (90 mg, 94%). 1H NMR (400 MHz, CDCl3) δ ppm 3.79 (s, 3 H) 6.21 (s, 1 H) 6.81 (d, J=8.1 Hz, 1 H) 6.93 (t, J=7.6 Hz, 1 H) 7.17-7.25 (m, 3 H) 7.35 (d, J=8.6 Hz, 1 H) 7.44 (d, J=2.0 Hz, 1 H) 7.70 (s, 1 H).

1. temperatureheated to reflux
2. washwashed with saturated aqueous sodium bicarbonate
3. dry with materialdried over sodium sulfate
4. concentrationconcentrated under vacuum