p-Toluenesulfonic acid → Diethyl furo[2,3-b]pyridine-5,6-dicarboxylate

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Reaction Steps

A xylene solution of the hydroxy-furo compound obtained in Example 23, (3.7 g) containing paratoluene sulfonic acid (0.01 g) is heated at reflux for two hours. The solution is cooled and the xylene solution decanted off. The residue is extracted with ether and the extracts combined with the xylene. Distillation of the solvents gives a yellow solid which is crystallized from a cyclohexane-toluene mixture to give pure diethyl furo[2,3-b]pyridine-5,6-dicarboxylate mp 66°-77° C.

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