3163-15-3

79-04-9

177210-33-2

General procedure for the synthesis of 5-hydroxy-2H-1,4-benzoxazin-3(4H)-ones from 2-aminoresorcinol and chloroacetyl chloride: 2-aminobenzene-1,3-diol (2.0 g, 16.0 mmol) and triethylamine (TEA, 1.94 g, 19.2 mmol) were dissolved in anhydrous N,N-dimethylformamide (DMF, 30 mL) and stirred until completely dissolved. 2-Chloroacetyl chloride (1.81 g, 16.0 mmol) was slowly added dropwise with stirring, and the reaction mixture was stirred for 16 hours at room temperature. Subsequently, potassium carbonate (K2CO3, 2.65 g, 19.2 mmol) was added and the mixture was stirred at the same temperature for another 16 hours. Upon completion of the reaction, the mixture was diluted with dichloromethane (DCM, 100 mL), washed twice sequentially with water and then with saturated brine. The organic phase was dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated. The obtained residue was purified by silica gel column chromatography to afford the target product 5-hydroxy-2H-1,4-benzoxazin-3(4H)-one (1.7 g, 64% yield).LCMS (m/z): 166.1 [M + H]+.