反应详情

3-(2,2-Diethoxy-ethoxy)-5-methoxy-benzoic acid methyl ester (6b) (1.95 g, 6.53 mmol) was added to a solution of polyphosphoric acid (1.47 g) in benzene (10 mL). The reaction mixture was heated to reflux for 2 hr, filtered and concentrated. The residue was purified by flash column chromatography (5% EtOAc in hexanes) to give a pale yellow solid (840 mg, 62% yield). 1H NMR (400 MHz, CDCl3) δ 7.64 (d, J=2.27 Hz, 1 H) 7.61 (d, J=2.27 Hz, 1 H) 7.26 (d, J=2.02 Hz, 1 H) 7.25 (d, J=2.27 Hz, 1 H) 3.99 (s, 3 H) 3.90 (s, 3 H).

1. temperatureThe reaction mixture was heated
2. temperatureto reflux for 2 hr
3. filtrationfiltered
4. concentrationconcentrated
5. customThe residue was purified by flash column chromatography (5% EtOAc in hexanes)