反应详情

To a solution of 1-ethyl-1H-pyrazole-5-carboxylic acid (950 mg) (for example, available from Fluorochem) in ethanol (50 ml) was added sulphuric acid (0.5 ml) and the mixture stirred at reflux under nitrogen for 70 h. The solvent was removed in vacuo and the residue partitioned between DCM (25 ml) and saturated sodium bicarbonate solution (25 ml) and separated using a hydrophobic frit. The aqueous layer was washed with DCM (2×20 ml) and the organic phases were combined. The solvent was removed in vacuo to give the title compound (1.09 g) as a colourless oil.

1. temperatureat reflux under nitrogen for 70 h
2. customThe solvent was removed in vacuo
3. customthe residue partitioned between DCM (25 ml) and saturated sodium bicarbonate solution (25 ml)
4. customseparated
5. washThe aqueous layer was washed with DCM (2×20 ml)
6. customThe solvent was removed in vacuo