Sodium Hydroxide → 1-Cyclohexyl-2-(4-oxo-2-phenyl-4H-chromen-6-yl)-1H-benzoimidazole-5-carboxylic Acid

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Reaction Steps

4-Oxo-2-phenyl-4H-chromene-6-carboxylic acid (280 mg, 1.05 mmol) was dissolved in DMF (5 mL), and HATU (418 mg, 1.1 eq.) and diisopropyl ethylamine (402 μL) were added. After stirring at room temperature for 15 minutes, 3-amino-4-cyclohexylamino-benzoic acid ethyl ester (303 mg, 1.1 eq.) dissolved in 2 mL DMF was added. After stirring overnight, the reaction was evaporated, dissolved in ethyl acetate and washed with water and brine, dried with sodium sulfate, evaporated and dried overnight. The product was then refluxed in acetic acid for 4h, evaporated to dryness, and coevaporated 2 more times with toluene. Saponification proceeds by dissolving the residue in ethanol (10 mL), adding 10 eq. of 1N NaOH solution and stirring at 40° C. for 4 hr. The ethanol was evaporated, water was added and acidified. The resulting precipitate was purified via reverse-phase HPLC. Yield: 58 mg

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