Potassium Dichromate → 7-Acetamido-2-methylquinoline-5,8-dione

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Reaction Steps

This compound was prepared by the oxidation of the corresponding acylamido with potassium dichromate in glacial acetic acid. Into a 1000 ml Erlenmeyer flask, 240 ml of glacial acetic acid, and 5,7-diacetamido-2-methyl-8-acetoxyquinoline (31) (prepared as described in Example 31) (6.3 g, 2.0 mmol) were added. To the resulting suspension, a solution of potassium dichromate (17.64 g) in 200 ml of water was added. This black solution was magnetically stirred at room temperature for 20-24 hours. The solution was then poured into 900 ml of water and extracted with dichloromethane (5×200 ml). The organic extracts were washed with a solution of 5% sodium carbonate in a saturated salt solution (3×300 ml). The organic layer was dried overnight with anhydrous magnesium sulfate. The magnesium sulfate was filtered off, and the solvent was evaporated to leave an orange/yellow solid. The solid 7-acetamino-2-methylquinoline-5,8-dione (27) was dried overnight under vacuum. 2.6 g of product was obtained for a yield of 56%.

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