反应详情

温度

135 °C

Phenyl hydrazine (2.94 ml, 0.03 moles) was dissolved in water (50 ml) in a 500 ml beaker. Concentrated H2SO4 (1.63 ml, 0.03 mole) was added drop-wise using a pipette while cooling with ice water bath. This phenyl hydrazine solution was then added to a stirred solution of sodium ethyl cyanopyruvate (5.37 g, 0.03 mole) in 70 ml of chloroform in a 500 ml round bottom flask at room temperature. Stirring was maintained for about 24 hrs and the reaction was monitored by LCMS. After the completion of reaction, the organic layer was separated and the aqueous layer was extracted with CHCl3 (2×150 ml). The combined organic layer was then washed with saturated NaHCO3 (1×100 ml), dried over sodium sulfate. Removal of solvent provided a viscous oil which was mainly non-cyclized hydrazone. The crude product was dissolved in minimum amount of dry EtOH (15 ml) and the mixture was heated in sealed tube at 120-150° C. for overnight. After the completion of reaction, ethanol was evaporated in vacuo to give crude product, which was purified by column chromatography eluting with Hexanes/Ethyl Acetate=9/1 to 1/1 to give 5.54 g of 5-Amino-1-phenyl-1H-pyrazole-3-carboxylic acid ethyl ester (yield: 80%).

1. temperaturewhile cooling with ice water bath
2. temperaturewas maintained for about 24 hrs
3. customAfter the completion of reaction
4. customthe organic layer was separated
5. extractionthe aqueous layer was extracted with CHCl3 (2×150 ml)
6. washThe combined organic layer was then washed with saturated NaHCO3 (1×100 ml)
7. dry with materialdried over sodium sulfate
8. customRemoval of solvent
9. customprovided a viscous oil which
10. customwas evaporated in vacuo
11. customto give crude product, which
12. customwas purified by column chromatography
13. washeluting with Hexanes/Ethyl Acetate=9/1 to 1/1