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ChemicalBook CAS DataBase List 1-METHYL-1H-PYRAZOLE-4-CARBOXYLIC ACID METHYL ESTER
5952-93-2

1-METHYL-1H-PYRAZOLE-4-CARBOXYLIC ACID METHYL ESTER synthesis

5synthesis methods
1-METHYL-1H-PYRAZOLE-4-CARBOXYLIC ACID

5952-92-1

(TRIMETHYLSILYL)DIAZOMETHANE

18107-18-1

1-METHYL-1H-PYRAZOLE-4-CARBOXYLIC ACID METHYL ESTER

5952-93-2

Step A: Trimethylsilylated diazomethane (12.0 mL, 24 mmol, 2.0 M hexane solution) was slowly added dropwise to a solution of 1-methyl-4-pyrazolecarboxylic acid (0.59 g, 4.7 mmol) in methanol (20 mL) at 0 °C through an addition funnel. The reaction mixture was stirred at the same temperature for 20 min followed by concentration. The crude product was partitioned between ethyl acetate (100 mL) and water (50 mL). The organic phase was dried over anhydrous sodium sulfate, filtered and concentrated. The crude product was purified by fast column chromatography using hexane/ethyl acetate (4:1, v/v) as eluent to afford methyl 1-methyl-1H-pyrazole-4-carboxylate (0.50 g, 3.6 mmol, 76% yield) as a white solid. Mass spectrum (APCI-positive ion mode) m/z: [M+1]+ = 141.1.

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Yield:5952-93-2 90%

Reaction Conditions:

with potassium carbonate in N,N-dimethyl-formamide at 20; for 1 h;

Steps:

131.1 first step 1-methyl-1H-pyrazole-4-carboxylate methyl ester

Methyl pyrazole-4-carboxylate 131a (5 g, 39.65 mmol) was dissolved in N,N-dimethylformamide (50 mL),Potassium carbonate (10.96 g, 79.29 mmol) and methyl iodide (6.19 g, 43.61 mmol) were sequentially added, and the reaction was stirred at room temperature for 1 hour.Water (50 mL) was added, extracted with ethyl acetate (50 mL×3), the organic phases were combined, washed successively with water (50 mL) and saturated sodium chloride solution (50 mL), dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure.The obtained residue was further separated and purified by silica gel column chromatography (eluent: system A),1-Methyl-1H-pyrazole-4-carboxylate methyl ester 131b (5.04 g) was obtained, yield: 90%.

References:

WO2022/57849,2022,A1 Location in patent:Page/Page column 166-167

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