4-Nitroanthranilic acid → 7-Nitroquinazolin-4(3H)-one

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Reaction Steps

4-Nitroanthranilic acid (10.0 g, 54.9 mmol) and formamidine hydrochloride (6.63 g, 82.4 mmol) were ground together in a mortar and pestle to produce a fine, intimate mixture. The mixture was placed in a 250 mL round-bottom flask, and spread evenly over the surface. The flask was placed in an oilbath at 200° C. The solid underwent a color change, and a distillate was seen on the side of flask, but did not really melt. After 30 min the flask was removed from the heating bath. 0.3M sodium hydroxide solution (150 mL) was added to the cooled flask, the black solid mass was broken up with a spatula, and stirred for 1 h. The solid was filtered off and washed with water. The filtrate was discarded. The black solid was suspended in dichloromethane/methanol (10:1) and filtered through a plug of silica, eluting with the same solvent until no more product came off. The material was one spot by TLC, plus black baseline material, but was poorly soluble, so a large volume of solvent was needed. The filtrate was evaporated to dryness and the solid residue triturated with a little methanol and filtered to give 7-nitroquinazoline-4-one (4.65 g, 44%).

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