p-Toluenesulfonic acid → Diethyl 2-ethyloxazolo[5,4-b]pyridine-5,6-dicarboxylate

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Reaction Steps

Diethyl 5-amino-1,6-dihydro-6-oxo-pyridine-2,3-dicarboxylate (7.57 g, 0.030 tool ), is suspended in 60 mL triethylorthopropionate (TEOP 0.30 mol). A small amount of p-toluenesulfonic acid is added and the mixture is heated at reflux for 65 hours. The triethylorthopropionate is removed in vacuo and the resulting oil is purified by column chromatography. The tractions containing the pure desired product are combined and stripped to a honey-colored oil weighing 7.38 g, yield 84.8%.

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