反应详情

A mixture of methyl 3-methylthiophene-2-carboxylate (13.2 mmol), N-Bromosuccinimide (13.2 mmol) and a catalytic amount of azobis-isobutyronitrile in carbon tetrachloride were heated at reflux under nitrogen. The reaction mixture was irradiated with a 500 W UV lamp for 1.5 hours, cooled down to room temperature and then filtered under autocup 0.45 μm, followed by the evaporation of the filtrate. The residue was purified by chromatography on silica gel (eluent: stepwise gradient of 3-5% diethyl ether in petroleum ether) to give 2.13 g of Intermediate IV.1 (69%), which was characterized by 1H NMR (CDCl3, 400 MHz) δ (ppm) 3.90 (s, 3H), 4.92 (s, 2H), 7.18 (d, J=5.3 Hz, 1H), 7.47 (d, J=5.3 Hz, 1H).

1. temperatureat reflux under nitrogen
2. customThe reaction mixture was irradiated with a 500 W UV lamp for 1.5 hours
3. filtrationfiltered under autocup 0.45 μm
4. customfollowed by the evaporation of the filtrate
5. customThe residue was purified by chromatography on silica gel (eluent