反应详情

Trichloromethyl chloroformate (9 mL, 75 mmol) was added slowly to a solution of 4-tert-butoxycarbonylamino-nicotinic acid (118) (16.2 g, 68 mmol) in dioxane and refluxed for 4 h under nitrogen atmosphere. The solution was cooled and the solvent was removed under vacuum. The residue was recrystallized by ether to yield 10.92 g (98%) of 1H-pyrido[4,3-d][1,3]oxazine-2,4-dione (119) as white solids. MP: 243° C.; 1H-NMR (DMSO-d6): ), δ 7.32 (d, J=6.0 Hz, 1H), 8.71 (d, J=6.0 Hz, 1H), 9.11 (s, 1H); EIMS m/z 165 (M+1).

1. temperaturerefluxed for 4 h under nitrogen atmosphere
2. temperatureThe solution was cooled
3. customthe solvent was removed under vacuum
4. customThe residue was recrystallized by ether