Hydrochloric Acid → Ethyl 2-methyl-4-(3-phenyl-quinolin-5-yl)-5-oxo-1,4,5,7-tetrahydrofuro[3,4-b]-pyridine-3-carboxylate

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Reaction Steps

1.4 g (6.0 mmol) of 3-phenylquinoline-5-aldehyde in 20 ml of ethanol are boiled with 0.79 ml (6.2 mmol) of ethyl acetate and 1.16 g (6.2 mmol) of ethyl 3-amino-4-acetoxycrotonate for 2 days. The mixture is cooled and concentrated. The residue is coarsely purified by flash chromatography. The intermediate obtained is boiled in a solution of 970 mg of potassium hydroxide in 50 ml of methanol for 40 minutes. The mixture is cooled, adjusted to pH 5 with 10% strength hydrochloric acid and concentrated, the residue is taken up in ethyl acetate and the solution is washed with water. The organic phase is dried and concentrated. The residue is freed from by-products by column chromatography, and the fractions are concentrated and crystallized from acetonitrile. 460 mg of colorless crystals of melting point 257-260° C. are obtained.

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