Dimethylformamide → 1-(2-Chloro-pyridin-3-yl)-1H-pyrrole-2-carbaldehyde

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Reaction Steps

To 14.6 g of N,N-dimethylformamide was added dropwise 8.3 g of phosphorus oxychloride under ice-cooling. The mixture was stirred at room temperature for 30 minutes. Thereto 6.5 g of 1-(2-chloro-3-pyridinyl)-1H-pyrrole was added, and the resulting mixture was stirred at 60° C. for 2 hours. The reaction mixture was allowed to cool to room temperature, and added to ice water. The mixture was adjusted to pH 4 by an addition of a 2N aqueous sodium hydroxide solution, and then extracted with ethyl acetate two times. The organic layers were combined, washed successively with water and an aqueous saturated sodium chloride solution, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The resulting residue was subjected to silica gel chromatography to obtain 6.05 g of 1-(2-chloro-3-pyridinyl)-1H-pyrrole-2-carbaldehyde of the formula:

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