Hydrochloric Acid → 7-hydroxy-2,3-dihydro-4H-chromen-4-one

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Reaction Steps

The crude 3-chloro-1-(2,4-dihydroxy-phenyl)-propan-1-one (6.9 g) is dissolved in sodium hydroxide (2N, 100 mL) at 0° C. The solution is stirred for 2 h and acidified with HCl (5N) to pH=3. The mixture is extracted with ethyl acetate (3×50 mL). The combined organic phase is washed with brine and dried over sodium sulfate. After evaporation of solvent, 7-hydroxy-chroman-4-one is obtained as yellow solid: 1H NMR (400 MHz, MeOD) δ 7.70 (d, 1H, J=8.8 Hz), 6.47 (dd, 1H, J=2.4, 8.8 Hz), 6.30 (d, 1H, J=2.0 Hz), 4.47 (t, 2H, J=6.4 Hz), 2.70 (t, 2H, J=6.4 Hz).

Provenance & Evidence