Dimethylformamide → 6-Formyl-4-ethoxy-quinoline-3-carboxylic acid ethyl ester

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Reaction Steps

A mixture of 6-iodo-4-ethoxy-quinoline-3-carboxylic acid ethyl ester (example 9a) (0.58 g, 1.56 mmol), triethylamine (0.54 mL, 3.91 mmol), diphenylpropylphosphine (dpp, 36 uL, 0.16 mmol) and palladium(II) acetate (35 mg, 0.16 mmol) in dry N,N-dimethylformamide (16 mL) in pressure tube was stirred under carbon monoxide at 75 psi at room temperature for 10 min. After addition of trihexylsilane (1.11 mL, 3.13 mmol), the mixture was then stirred under carbon monoxide at 75 psi at 80° C. for 3 h. The reaction was allowed to cool to 25° C. and then extracted with methylene chloride (2×100 mL). The combined organic layers were successively washed with a saturated aqueous sodium bicarbonate solution (3×50 mL) and water (3×50 mL), dried over sodium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 70-230 mesh, 0%-40% ethyl acetate in hexanes in 30 min) afforded 6-formyl-4-ethoxy-quinoline-3-carboxylic acid ethyl ester (0.25 g, 59%) as a white solid.

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