Réaction #792174

Équation de réaction

Potassium persulfate

ethyl 2-(3-chloro-2-pyridinyl)-5-oxo-3-pyrazolidinecarboxylate

sulfuric acid

→

precipitate

Rendement 15.7%

Ethyl 1-(3-chloro-2-pyridinyl)-2,3-dihydro-3-oxo-1H-pyrazole-5-carboxylate

Rendement 15.7%

Solvants

acetonitrile

Conditions de réaction

Traitement

1. 1
   AutreThe reaction mixture thinned to form a pale green, nearly clear solution
2. 2
   Autreto form a pale yellow suspension
3. 3
   Températurethe reaction mixture was heated
4. 4
   Températureat gentle reflux for 3.5 hours
5. 5
   TempératureAfter cooling
6. 6
   Autrea precipitate of white solid was removed by filtration
7. 7
   workup.ADDITIONThe filtrate was diluted with water (400 mL)
8. 8
   Extractionextracted three times with ethyl ether (700 mL total)
9. 9
   Autreprecipitation of an off-white solid (3.75 g), which
10. 10
    Filtrationwas collected by filtration
11. 11
    ConcentrationThe ether mother liquor was further concentrated

Mode opératoire

To a suspension of ethyl 2-(3-chloro-2-pyridinyl)-5-oxo-3-pyrazolidinecarboxylate (i.e. product of Example 12, Step A) (27 g, 100 mmol) stirred in dry acetonitrile (200 mL) was added sulfuric acid (20 g, 200 mmol) in one portion. The reaction mixture thinned to form a pale green, nearly clear solution before thickening again to form a pale yellow suspension. Potassium persulfate (33 g, 120 mmol) was added in one portion, and then the reaction mixture was heated at gentle reflux for 3.5 hours. After cooling using an ice bath, a precipitate of white solid was removed by filtration and discarded. The filtrate was diluted with water (400 mL) and then extracted three times with ethyl ether (700 mL total). Concentration of the combined ether extracts to a reduced volume (75 mL) caused precipitation of an off-white solid (3.75 g), which was collected by filtration. The ether mother liquor was further concentrated to yield a second crop of an off-white precipitate (4.2 g), which was also collected by filtration. An off-white solid also precipitated from the aqueous phase; this solid (4.5 g) was collected by filtration to provide a combined total of 12.45 g of the title compound.

Source