General procedure for the synthesis of 5-chloro-1-methyl-1H-benzo[d][1,3]oxazine-2,4-diones from 5-chloro-1H-benzo[d][1,3]oxazine-2,4-diones and iodomethane: Iodomethane (2 mL, 4.6 mmol, 4 equiv) and N,N-diisopropylethylamine (DIPEA, 1 mL, 0.74 mol) were suspended at room temperature in N,N-dimethylacetamide (DMA, 10 mL) and stirred for 10 min. Subsequently, 5-chloroisatoic anhydride (200 mg, 1.01 mmol, 1 eq.) was added and the reaction mixture was stirred at 40 °C for 5 hours. Upon completion of the reaction, the resulting product 5-chloro-1-methyl-1H-benzo[d][1,3]oxazine-2,4-dione was collected by filtration and washed with distilled water to give the pure product (150 mg, 70% yield). The melting point of the product was 224 °C. Infrared spectra (KBr) showed characteristic absorption peaks υ1774, 1716, 1593 cm^-1. 1H NMR (DMSO-d6, 300 MHz) δ 7.78 (t, J = 8.1 Hz, 1H), 7.42 (m, 2H), 3.45 (s, 3H). Elemental analysis results: calculated values for C9H6ClNO3: C, 51.08; H, 2.86; Cl, 16.75; N, 6.62; O, 22.68. measured values: C, 51.12; H, 2.36; Cl, 16.71; N, 6.58.
![5-CHLORO-1-METHYL-1H-BENZO[D][1,3]OXAZINE-2,4-DIONE](/CAS/GIF/40707-01-5.gif)