Potassium Hydroxide → HCID 23669974, compound

Participants

Reaction Steps

A solution of 4-oxo-4H,5H-[1]benzopyrano[4,3-b]pyran-2-carboxylic acid methyl ester (0.292 g, 1.1 moles, described in Example 6) in methanol (15 ml) containing potassium hydroxide (0.2 g) is stirred at room temperature overnight. The solution is evaporated under reduced pressure and the residue is crystallized from methanol to give 4-oxo-4H,5H-[1]benzopyrano[4,3-b]pyran-2-carboxylic acid potassium salt; m.p. > 280° C, νmaxnujol 1650 cm-1. The latter compound is dissolved in water and the resulting solution is added to dilute hydrochloric acid. The precipitate is collected and crystallized from methanol to give the title compound; m.p. 253°-254° C (dec.), νmaxnujol 2500, 1735 and 1650 cm-1.

Provenance & Evidence