Hydrochloric Acid → Ethyl 2-(3-Chloro-2-pyridinyl)-5-oxo-3-pyrazolidinecarboxylate

関与物質

反応条件

反応手順

To a mixture of 20 g of 3-chloro-2-hydrazinopyridine, 56 ml of sodium ethoxide (a 21% solution in ethanol) and 75 ml of ethanol was added dropwise 27 ml of diethyl maleate. The resulting mixture was heated to reflux for 10 minutes. The reaction mixture was allowed to cool to 65° C., and 15 ml of acetic acid was poured into the mixture. The reaction mixture was allowed to cool to room temperature. After 190 ml of water was poured into the reaction mixture, the mixture was adjusted to pH 2 by an addition of 6N hydrochloric acid and then extracted with methyl tert-butyl ether three times. The organic layers were combined, washed with an aqueous saturated sodium chloride solution, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. Diethyl ether was added to the resulting residue, and a solid was collected by filtration to obtain 4.28 g of ethyl 2-(3-chloro-2-pyridinyl)-5-oxo-3-pyrazolidinecarboxylate of the formula:

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