5-Chloro-3,1-benzoxazin-2,4-dione

75-44-5

2148-56-3

20829-96-3

In a 250 mL round-bottomed flask under nitrogen protection, 2-amino-6-chlorobenzoic acid (11.69 g, 68 mmol) was dissolved in 100 mL of 1,4-dioxane. After cooling the reaction system to 0°C, phosgene (36 mL, 68 mmol) was slowly added through a dropping funnel. The reaction mixture was stirred at 0°C for 24 h, followed by natural warming to 23°C (room temperature). Upon completion of the reaction, the resulting white solid product was collected by filtration and washed sequentially with 1,4-dioxane and ether to afford 5-chloro-1H-benzo[d][1,3]oxazine-2,4-dione (12.5 g, 93% yield).