反应详情

To a solution of 5-hydroxy-benzofuran-2-carboxylic acid (4.6 g, 26.0 mmol) in MeOH (100 mL) was added concentrated sulfuric acid (1.2 g, 13.0 mmol) and the resultant solution was heated (reflux, 18 h). The reaction was cooled (rt) and concentrated in vacuo. The resultant residue was purified by silica gel flash column chromatography using MeOH:DCM (10%) to provide the title compound (4.14 g, 83%). MS (ESI): mass calcd for C10H8O4, 192.0; m/z found, 193.1 [M+H]+. 1H NMR (500 MHz, CD3OD): 7.47 (s, 1H), 7.39 (d, J=9.0, 1H), 7.04 (d, J=2.5, 1H), 6.97 (dd, J=9.0, 2.5, 1H), 3.92 (s, 3H).

1. temperature(reflux, 18 h)
2. concentrationconcentrated in vacuo
3. customThe resultant residue was purified by silica gel flash column chromatography