Hydrochloric Acid → 9-[(2-Trifluoromethylphenyl)methyl]-4-hydroxy-5-carbamoyl carbazole

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A solution of the 9-[(2-trifluoromethylphenyl)methyl]-4-hydroxy-5-carbomethoxy carbazole (310 mg, 0.77 mM) in 5 mL THF and 20 mL concentrated aqueous ammonium hydroxide was sonicated for 25 hours at 40-50° C. The mixture was diluted with ethyl acetate and acidified to pH 1 with 5 N HCl. The aqueous layer was extracted twice with ethyl acetate. The combined organic extracts were washed with saturated brine, dried over magnesium sulfate, filtered, and concentrated. The residue was purified by column chromatography on silica gel (elution with gradient methylene chloride/ethyl acetate) to afford 145 mg (49%) of the 9-[(2-trifluoromethylphenyl)methyl]-4-hydroxy-5-carbamoyl carbazole as a white solid. 1H NMR (DMSO-d6) δ10.5 (s, 1H), 8.8 (br s, 1H), 8.4 (br s, 1H), 7.8 (d, 1H, J=8 Hz), 7.6-7.2 (m, 6H), 6.85 (d, 1H, J=8 Hz), 6.6 (d, 1H, J=8 Hz), 6.25 (d, 1H, J=8 Hz), and 5.8 (s, 2H). IR (KBr, cm−1) 3460, 3360, and 1589. MS (ES) m/e 383, 385.

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