Pyridine → 2,6-Dichloro-3-nitrophenylacetic acid iodopropargyl ester

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15 g (0.06 moles) of 2,6-dichloro-3-nitrophenylacetic acid were suspended in 30 ml of cyclohexane and 20 ml of thionyl chloride. The whole was refluxed until the evolution of gas was complete. Subsequently, excess thionyl chloride and cyclohexane were distilled off. The resulting acid chloride was dissolved in 50 ml of absolute toluene and, while stirring, at a temperature of 30° C., added dropwise to a mixture of 11 g (0.06 moles) of 3-iodopropynol, 4.75 g of pyridine and 50 g of toluene. After 1 hour the reaction mixture was taken up in diethyl ether and the ethereal solution was extracted with 1N hydrochloric acid and then with saturated sodium bicarbonate solution. Finally, the organic phase was washed with water, dried with sodium sulfate and concentrated by evaporation. The crude product (22.7 g) was further purified by chromatography over silica gel. 15.5 g (0.037 moles) of 2,6-dichloro-3-nitrophenylacetic acid iodopropargyl ester corresponding to 63% of the theoretical yield, were obtained. Melting range 97°-99° C.

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