Reaktion #1260725

Reaktionsgleichung

crude product

methyl 2-bromo-4-chloro-4-oxobutanoate

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

(3-chloro-pyridin-2-yl)-hydrazine

sodium bicarbonate

→

title compound

Ausbeute 89.8%

methyl 2-(3-chloro-2-pyridinyl)-5-oxo-3-pyrazolidine-carboxylate

Ausbeute 89.8%

Lösungsmittel

acetonitrile

acetonitrile

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturThe mixture was then warmed
2. 2
   Temperaturmaintained at 38° C. for 8 h
3. 3
   Temperaturto cool
4. 4
   Sonstigethe solvent was removed by evaporation under reduced pressure
5. 5
   workup.ADDITIONWater (25 mL) was added
6. 6
   workup.ADDITIONacetic acid (about 1.9 mL) was added until the slurry
7. 7
   workup.WAITAfter 2 h
8. 8
   Sonstigethe product was isolated by filtration
9. 9
   Waschenrinsed with water (10 mL)
10. 10
    Sonstigedried in vacuo

Vorschrift

The crude product of Step B (i.e. methyl 2-bromo-4-chloro-4-oxobutanoate) (11.00 g, ˜47.4 mmol) in acetonitrile (25 mL) was added over 65 minutes to a mixture of 3-chloro-2(1H)-pyridinone hydrazone (alternatively named (3-chloro-pyridin-2-yl)-hydrazine) (6.55 g, 45.6 mmol) and sodium bicarbonate (9.23 g, 0.110 mol) in acetonitrile (60 mL) at 0° C. The mixture was then allowed to warm to room temperature and was stirred for 3 h. The mixture was then warmed and maintained at 38° C. for 8 h. Then the mixture was allowed to cool, and the solvent was removed by evaporation under reduced pressure. Water (25 mL) was added, and acetic acid (about 1.9 mL) was added until the slurry had a pH of about 5. After 2 h, the product was isolated by filtration, rinsed with water (10 mL) and dried in vacuo to provide the title compound as a pale yellow solid (11 g, 89.8% yield). A sample recrystallized from ethanol melted at 147-148° C.

Quelle