Ethyl pyrazole-4-carboxylate synthesis
- Product Name:Ethyl pyrazole-4-carboxylate
- CAS Number:37622-90-5
- Molecular formula:C6H8N2O2
- Molecular Weight:140.14
80370-42-9
37622-90-5
The general procedure for the synthesis of ethyl 4-pyrazolecarboxylate from ethyl 2-formyl-3-oxopropanoate was as follows: 6.2 g (193 mmol) of hydrazine was slowly added to a solution of 27.6 g (192 mmol) of (ethoxycarbonyl)malondialdehyde dissolved in 150 mL of ethanol under ice bath cooling conditions. The reaction mixture was stirred at room temperature for 17 hours to complete the reaction. Subsequently, ethanol was removed from the reaction mixture by vacuum distillation. The residue was purified by silica gel column chromatography using a solvent mixture of dichloromethane and ethyl acetate as the unfolding agent, resulting in 19.4 g (72.4% yield) of ethyl 1H-pyrazole-4-carboxylate as yellow crystals.1H-NMR [CDCl3/TMS, δ (ppm)]: 8.08 (2H, s), 5.30 (1H, s), 4.31 ( 2H, q), 1.36 (3H, t).
37718-11-9
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64-17-5
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37622-90-5
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Yield:37622-90-5 80%
Reaction Conditions:
with thionyl chloride at 0 - 20; for 3 h;
Steps:
29 ethyl 1H-pyrazole-4-carboxylate (50-2)
[0134] To a solution of 1H-pyrazole-4-carboxylic acid (50-1, 1 g, 8.92 mmol) in EtOH (10 mL) was added thionyl chloride (1.6 g, 13.38 mmol) at 0oC and the mixture was stirred at rt for 3h. The progress of the reaction was monitored by TLC. After completion of the reaction, all the volatiles were evaporated to dryness. The mixture was diluted with water and extracted with EtOH/DCM (10%). The combined organic layers were washed with water and brine, dried over anhydrous Na2SO4 and concentrated under reduced pressure. The crude compound was purified by silica gel column chromatography (15% EtOAc/hexane) to afford compound 50-2 (1.0 g, 80.0%) as an off white solid. LC-MS: m/z 141. 0 [M+H]+.
References:
WO2021/102410,2021,A1 Location in patent:Paragraph 0134
80370-42-9
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37622-90-5
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105-56-6
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37622-90-5
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