反応 #1435692

反応方程式

diethyl maleate

sodium ethoxide

acetic acid

3-chloro-2(1H)-pyridinone hydrazone

→

title product

Ethyl 2-(3-Chloro-2-pyridinyl)-5-oxo-3-pyrazolidinecarboxylate

溶媒

water

ethanol

反応条件

後処理

1. 1
   その他A 2-L four-necked flask equipped with a mechanical stirrer
2. 2
   workup.ADDITIONthermometer, addition funnel
3. 3
   温度reflux condenser, and nitrogen inlet
4. 4
   温度The mixture was heated
5. 5
   温度The mixture was re-heated
6. 6
   温度to reflux over a period of 5 minutes
7. 7
   温度The reflux rate increased markedly during the addition
8. 8
   workup.ADDITIONBy the end of the addition all of the starting material
9. 9
   workup.DISSOLUTIONhad dissolved
10. 10
    温度at reflux for 10 minutes
11. 11
    温度After being cooled to 65° C.
12. 12
    その他A precipitate formed
13. 13
    workup.DISSOLUTIONto dissolve
14. 14
    温度The orange solution was cooled in an ice bath
15. 15
    その他to precipitate at 28° C
16. 16
    その他The product was isolated via filtration
17. 17
    洗浄washed with aqueous ethanol (40%, 3×50 mL)
18. 18
    その他air-dried on the
19. 19
    ろ過filter for about 1 hour

実験手順

A 2-L four-necked flask equipped with a mechanical stirrer, thermometer, addition funnel, reflux condenser, and nitrogen inlet was charged with absolute ethanol (250 mL) and an ethanolic solution of sodium ethoxide (21%, 190 mL, 0.504 mol). The mixture was heated to reflux at about 83° C. It was then treated with 3-chloro-2(1H)-pyridinone hydrazone (68.0 g, 0.474 mol). The mixture was re-heated to reflux over a period of 5 minutes. The yellow slurry was then treated dropwise with diethyl maleate (88.0 mL, 0.544 mol) over a period of 5 minutes. The reflux rate increased markedly during the addition. By the end of the addition all of the starting material had dissolved. The resulting orange-red solution was held at reflux for 10 minutes. After being cooled to 65° C., the reaction mixture was treated with glacial acetic acid (50.0 mL, 0.873 mol). A precipitate formed. The mixture was diluted with water (650 mL), causing the precipitate to dissolve. The orange solution was cooled in an ice bath. Product began to precipitate at 28° C. The slurry was held at about 2° C. for 2 hours. The product was isolated via filtration, washed with aqueous ethanol (40%, 3×50 mL), and then air-dried on the filter for about 1 hour. The title product compound was obtained as a highly crystalline, light orange powder (70.3 g, 55% yield). No significant impurities were observed by 1H NMR.

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