Sodium Hydroxide → 5H-pyrimido-[4,5-b][1,4]oxazin-6-one

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Reaction Steps

In a 25 ml flask, (6-chloro-5-nitro-pyrimidin-4-yloxy)-acetic acid methyl ester (280 mg, 1.1 mmol) and tin tetrachloride (849 mg, 4.5 mmol) were dissolved in hydrochloric acid (7 ml) and heated for 1 hour at 80□. The reaction mixture was cooled to room temperature and neutralized by adding 10% sodium hydroxide solution dropwise, and the formed solid was removed by filtration. The filtrate was extracted with ethyl acetate, and the combined organic layer was washed with saturated saline solution, dried over anhydrous sodium sulfate (Na2SO4), filtered and evaporated under reduced pressure. The obtained yellow solid mixture (107 mg) was used in the next step without further purification.

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