Reaktion #41164

Reaktionsgleichung

Cyclopentyl-hydrazine hydrochloride

ethyl (ethoxymethylene)-cyanoacetate

sodium acetate

→

5-amino-1-cyclopentyl-1H-pyrazole-4-carboxylic acid ethyl ester

Ausbeute 79.3%

Lösungsmittel

ethanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturAfter cooling to room temperature
2. 2
   Sonstigeethanol was removed in vacuo
3. 3
   Sonstigethe residue was partitioned between methylene chloride and water
4. 4
   WaschenThe organic phase was washed sequentially with water and brine
5. 5
   ExtraktionEach aqueous phase was back extracted with a single portion of methylene chloride
6. 6
   Trocknendried over sodium sulfate
7. 7
   Einengenconcentrated
8. 8
   SonstigePurification by flash chromatography
9. 9
   Wascheneluting with 10-40% EtOAc/hexanes

Vorschrift

Cyclopentyl-hydrazine hydrochloride (1.000 g; 7.32 mmol), ethyl (ethoxymethylene)-cyanoacetate (1.026 g, 6.61 mmol) and anhydrous sodium acetate (0.644 g, 7.85 mmol) were combined in ethanol (10 mL) and heated at 70° C. for 20 hours. After cooling to room temperature, ethanol was removed in vacuo and the residue was partitioned between methylene chloride and water. The organic phase was washed sequentially with water and brine. Each aqueous phase was back extracted with a single portion of methylene chloride. The two organic phases were combined, dried over sodium sulfate and concentrated. Purification by flash chromatography, eluting with 10-40% EtOAc/hexanes yielded 5-amino-1-cyclopentyl-1H-pyrazole-4-carboxylic acid ethyl ester (1.170 g, 73%). Mass spectrum: m/z: 224.1 (M+H).

Quelle