反应详情

To a solution of 3-[4-(1-ethoxycarbonyl-ethyl)-7-fluoro-3-oxo-3,4-dihydro-2H-benzo[1,4]oxazin-6-yloxy]-3-methyl-azetidine-1-carboxylic acid tert-butyl ester (0.164 g, 0.362 mmol) in toluene (3 mL) and DME (3 mL) was added Lawesson's reagent (0.117 g, 0.290 mmol) and the mixture was heated to reflux for 4 h. The mixture was cooled to ambient temperature and concentrated in vacuo. The residue was purified by column chromatography on silica gel (eluting with 5% to 10% EtOAc in petroleum ether) to give 3-[4-(1-ethoxycarbonyl-ethyl)-7-fluoro-3-thioxo-3,4-dihydro-2H-benzo[1,4]oxazin-6-yloxy]-3-methyl-azetidine-1-carboxylic acid tert-butyl ester (0.080 g, 47%) as a pale yellow solid. 1H NMR (CDCl3, 400 MHz): δ 6.82 (d, J=10.0 Hz, 1H), 6.72 (brs, 1H), 6.47 (d, J=6.8 Hz, 1H), 4.89 (d, J=13.2 Hz, 2H), 4.16 (m, 4H), 3.85 (m, 2H), 1.64 (d, J=7.2 Hz, 3H), 1.56 (s, 3H), 1.43 (s, 9H), 1.16 (t, J=6.8 Hz, 3H).

1. temperaturethe mixture was heated
2. temperatureto reflux for 4 h
3. concentrationconcentrated in vacuo
4. customThe residue was purified by column chromatography on silica gel (eluting with 5% to 10% EtOAc in petroleum ether)