Hydrochloric Acid → 6-Methoxythianaphthen-2-one

Participants

Reaction Steps

To tetrahydrofuran (200 ml) containing 2-dimethylamino-6-methoxybenzo[b] thiophene (20.00 g, 96.5 mmol) is added 1N aqueous hydrochloric acid (200 ml) and the resulting mixture is heated to reflux for 3 hours. The mixture is cooled, the layers are separated, and the aqueous layer is extracted with methylene chloride (300 ml). The combined organic layers washed with water (250 ml), dried over magnesium sulfate, filtered and concentrated to give crude product, which is recrystallized from ethanol, and dried in vacuo at room temperature to afford the title compound (13.89 g, 77.0 mmol, 80%): mp 80-82° C.; IR (KBr) 1713, 1605, 1485, 1287, 1015, 865, 813 cm-1 ; 1H NMR (DMSO-d6) δ7.22 (d, 1 H, J=8.4 Hz), 7.11 (s, 1 H), 6.78 (d, 1 H, J=8.4 Hz), 4.06 (s, 2 H), 3.71 (s, 3 H); 13C NMR (DMSO-d6) d 203.5, 159.0, 136.9, 125.6, 124.6, 112.3, 108.4, 55.3, 46.2. Anal. Calcd. for C9H8O2S: C, 59.98; H, 4.47; S, 17.78. Found: C, 60.19; H, 4.57; S, 18.03.

Provenance & Evidence