24036-52-0

General procedure for the synthesis of 6-bromo-2H-1,4-benzoxazin-3(4H)-one from 2-amino-4-bromophenol and chloroacetyl chloride: triethylamine (TEA, 4.06 g, 40 mmol) was added to a tetrahydrofuran (THF, 150 mL) solution of 2-amino-4-bromophenol (5 g, 27 mmol). Subsequently, chloroacetyl chloride (3.33 g, 30 mmol) was added in batches at 0 °C. After 20 min of reaction, the mixture was continued to be stirred for 2 h at room temperature. The reaction mixture was again cooled to 0 °C and sodium hydride (NaH, 60% dispersed in mineral oil, 2.2 g, 54 mmol) was added in batches. After stirring at 0 °C for 20 min, the reaction mixture was brought to room temperature and stirring was continued for 2 h. The reaction mixture was then quenched with water. After completion of the reaction, the reaction was quenched with water. The solvent was removed by distillation under reduced pressure and the resulting residue was diluted with water. The precipitate was collected by filtration, washed with water and dried under vacuum to afford 6-bromo-2H-1,4-benzoxazin-3(4H)-one (5.5 g, 89% yield).

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