Hydrochloric Acid → 4-Oxo-4H, 5H-[1]benzopyrano [4,3-b]pyran-2-carboxylic Acid Methyl Ester

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Reaction Steps

A solution of 4-(4-chromanone-3-yl)-2,4-dioxobutyric acid ethyl ester [0.70 g, 2.4 mmoles, described above in (a)] in methanol is saturated with hydrogen chloride gas. The solution is heated at reflux temperature overnight and evaporated to dryness. The residue is chromatographed on silica gel using benzene-ethyl acetate (4:1). The eluate is evaporated and the residue is crystallized from chlorofrom-ether to give the title compound, m.p. 173°-174° C.

Provenance & Evidence