Réaction #41102

Équation de réaction

5-Chloro-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester

Sodium hydride

pyrazole

Water

→

2′-methyl-2′H-[1,3′]bipyrazolyl-4′-carboxylic acid ethyl ester

Rendement 9.1%

Solvants

DMF

ethyl acetate

Conditions de réaction

Traitement

1. 1
   Températurethe mixture was heated to 100° C. overnight
2. 2
   Températurecooled
3. 3
   Autrethe organic layer was separated
4. 4
   Extractionthe aqueous phase was extracted three times with EtOAc
5. 5
   ConcentrationThe combined organic phases were concentrated in vacuo
6. 6
   Autrethe residue was purified by flash silica chromatography
7. 7
   Lavageeluting with a gradient of 0-20% ethyl acetate/hexanes

Mode opératoire

Sodium hydride (60% in oil; 767 mg, 19 mmol) was added to a solution of pyrazole (1.36 g, 20 mmol) in dry DMF (40 mL) under nitrogen at 0° C. in an ice-water bath and the mixture was heated to 40° C. for 1 h. 5-Chloro-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester (1.89 g, 10 mmol) was added and the mixture was heated to 100° C. overnight and then cooled. Water and ethyl acetate were added, the organic layer was separated, and the aqueous phase was extracted three times with EtOAc. The combined organic phases were concentrated in vacuo and the residue was purified by flash silica chromatography eluting with a gradient of 0-20% ethyl acetate/hexanes, then 20% ethyl acetate/hexanes to give 2′-methyl-2′H-[1,3′]bipyrazolyl-4′-carboxylic acid ethyl ester (0.2 g, 9%).

Source