Potassium Carbonate → 10-bromo-2-(3-carboxy-1-trans-propenyloxy)-5-(3-pyridylmethyl)-4H-pyrido[3,2,1-jk]carbazole-4-one

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Reaction Steps

10-bromo-2-hydroxy-5-(3-pyridylmethyl)-4H-pyrido[3,2,1-jk]carbazole-4-one (400 mg) obtained in Example 2 was suspended in dimethyl sulfoxide (30 ml), and to the suspension was added potassium carbonate (0.3 g), and the mixture was stirred at room temperature for 30 minutes. Ethyl 4-bromocrotonate (0.15 ml) was added and the mixture was stirred at room temperature for 12 hours. The reaction mixture was poured into ice water (300 ml), and extracted with ethyl acetate. The ethyl acetate layer was washed with saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure. The residue was purified by silica gel flash column chromatography (eluent: ethyl acetate). The resulting crude crystals were suspended in ethanol (20 ml), and 1N aqueous solution of sodium hydroxide (5 ml) was added to the suspension followed by stirring at room temperature for 12 hours. The solvent was evaporated under reduced pressure and the residue was extracted with water and ethyl acetate. 1N hydrochloric acid was added to the aqueous layer to a pH of 7, and the precipitated crystals were recovered by filtration to obtain the title compound (50 mg, 10%).

Provenance & Evidence