Potassium Hydroxide → 9-(1,3-Benzodioxol-5-yl)-8-methoxycarbonyl-benzo[g][1,3]benzodioxole-7-carboxylic acid

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Reaction Steps

Compound 30 (20 mg, 0.05 mmol) was refluxed with 1 M solution of KOH in MeOH (10 mL) for 2 h. The solution was cooled, and the solvent was removed under reduced pressure. The remaining solid was dissolved in water (10 mL) and then acidified to pH 1-2 with 10% aqueous HCl solution. The precipitate was collected by filtration, washed with water, and dried. The product was purified by column chromatography on silica gel using CH2Cl2/MeOH (20:1 to 10:1, v/v) to give 31 (11 mg, 56%) as a pale yellow powder. mp 273-275° C.; 1H NMR (CDCl3) δ 8.54 (s, 1H, H4), 7.49 (d, 1H, H5, J=8.1 Hz), 7.20 (d, 1H, H6, J=8.1 Hz), 6.76-6.82 (m, 3H, H2′+H5′+H6′), 6.03 (AB, 2H, 3′,4′-OCH2O—, Δδ=11.1 Hz), 5.88 (AB, 2H, 7,8-OCH2O—, Δδ=7.2 Hz), 3.62 (s, 3H, OCH3); MS (FAB, positive) m/z 395 [M+H]+.

Provenance & Evidence