Hydrochloric Acid → Ethyl 6-amino-8-methoxycarbonyl-4-oxo-10-propyl-4H-pyrano[3,2-g]quinoline-2-carboxylate

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Reaction Steps

4-Chlorophenoxysulphonylisocyanate (0.2 ml, 290 mg) was added to a suspension of ethyl 6,9-dihydro-4,6-dioxo-8-methoxycarbonyl-10-propyl-4H-pyrano[3,2-g]quinoline-2-carboxylate (385 mg, 1 mmol) in acetonitrile (5 ml), and then refluxed for 0.5 h. The solution was allowed to cool, ethanolic hydrogen chloride solution (2 ml) was added, and after 5 minutes the pale yellow solution was poured into aqueous ammonial solution (0.88 specific gravity, 5 ml) at 5° C., to give a thick orange precipitate. Filtration and washing with ethanol (10 ml) gave the title compound, 320 mg (83%) as an orange powder, mp 268°-270° C. (decomposes).

Provenance & Evidence