Nitroethane → Ethyl 3,5-dimethylisoxazole-4-carboxylate

Beteiligte Stoffe

Reaktionsschritte

A solution of the ethyl β-pyrrolidinocrotonate (427 g. = 2.33 moles), 190 ml. (182 g., 2.43 mole) of nitroethane and 1300 ml. of triethylamine in 1200 ml. of anhydrous chloroform was cooled in an ice bath under nitrogen. A solution of 235 ml. (393 g. = 2.56 mole) of phosphorus oxychloride in 400 ml. of chloroform was added at such a rate that the temperature did not rise above 15°. During the addition, which took place over a three-hour period, a viscous orange precipitate formed. This suspension was then stirred under nitrogen overnight. As much solvent as possible was removed at reduced pressure and the resulting red-brown paste was diluted with water and extracted with ether. The ether solutions were washed sequentially with water, 3N hydrochloric acid, water, 5 percent sodium hydroxide solution and water, and were dried over anhydrous sodium sulfate. Solvent removal at reduced pressure gave a dark oil which was distilled through a short Vigreux column to give 4-carboethoxy-3,5-dimethyl-isoxazole as a slightly cloudy, colorless liquid of b.p. 100°/11 mm.

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