Hydrochloric Acid → 6-Oxo-2H,6H-[1,3]dioxolo[4,5-g][1]benzopyran-7-carboxylic acid

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Reaction Steps

To a suspension of ethyl 6,7-methylenedioxy-2-oxo-1-benzopyran-3-carboxylate (0.26 g) in methanol (20 ml), 2N KOH (1.5 ml) was added, followed by stirring at room temperature for 2 hours. The reaction mixture was poured into water and acidified with hydrochloric acid; the resulting crystal was collected by filtration to yield 6,7-methylenedioxy-2-oxo-1-benzopyran-3-carboxylic acid (0.1 g, 44%), which was then recrystallized from N,N-dimethylformamide-water to yield yellow prisms having a melting point of 279°-280° C.

Provenance & Evidence