Réaction #41164

Équation de réaction

Cyclopentyl-hydrazine hydrochloride

ethyl (ethoxymethylene)-cyanoacetate

sodium acetate

→

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

Rendement 79.3%

Solvants

ethanol

Conditions de réaction

Traitement

1. 1
   TempératureAfter cooling to room temperature
2. 2
   Autreethanol was removed in vacuo
3. 3
   Autrethe residue was partitioned between methylene chloride and water
4. 4
   LavageThe organic phase was washed sequentially with water and brine
5. 5
   ExtractionEach aqueous phase was back extracted with a single portion of methylene chloride
6. 6
   Séchagedried over sodium sulfate
7. 7
   Concentrationconcentrated
8. 8
   AutrePurification by flash chromatography
9. 9
   Lavageeluting with 10-40% EtOAc/hexanes

Mode opératoire

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).

Source