p-Toluenesulfonic acid monohydrate → racemic methyl 2-(3,4-dichlorophenyl)-2H-chromene-3-carboxylate

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Reaction Steps

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).

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