反应详情

To a mixture of benzene (200 mL) containing polyphosphoric acid (80 g, 236.69 mmol) was added 2-(4-fluoro-phenoxy)-acetaldehyde diethyl acetal (45 g, 197.37 mmol). The mixture was stirred vigorously while being heated to reflux for 2.5 hours. The reaction mixture was cooled to room temperature and decanted from the polyphosphoric acid. The solvent was removed under vacuum to give the residue, which was purified by a silica gel column with 1% ethyl acetate in petroleum ether to afford 5-fluorobenzofuran as colorless oil (14.0 g, crude).

1. temperaturewhile being heated
2. temperatureto reflux for 2.5 hours
3. customdecanted from the polyphosphoric acid
4. customThe solvent was removed under vacuum
5. customto give the residue, which
6. customwas purified by a silica gel column with 1% ethyl acetate in petroleum ether