Toluene → 6-methoxy-2,4-dihydro-1H-3,1-benzoxazine-2,4-dione

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Reaction Steps

To a mixture of 10.0 g (60.0 mmol) of 5-methoxyanthranilic acid in 80 mL of 1,4-dioxane was slowly added 100 mL (193 mmol) of a 1.93 molar solution of phosgene, or thiophosgene in an inert solvent, preferably a hydrocarbon solvent such as toluene, at room temperature. The mixture was stirred overnight at room temperature. This mixture was then concentrated in vacuo to a small volume. This concentrated reaction mixture was filtered through silica and the filter cake was washed with hexane to give 10.99 g (95.2%) of the 5-methoxyisatoic anhydride as an off white solid. MS (Cl mode) m/z 176 (M-18, 100%), 194 (M+H, 71%).

Provenance & Evidence