Sodium hydride → 4-nitro-2-(2-trimethylsilanyl-ethoxymethyl)-2H-pyrazole-3-carboxylic acid, ethyl ester

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Reaction Steps

To a 0° C. solution of 4-nitro-1H-pyrazole-3-carboxylic acid ethyl ester (6.4 g, 34.58 mmol) in dimethylformamide (80 mL) was added sodium hydride (2.07 g, 1.5 eq), and the resulting mixture was stirred from 0° C. to room temperature for one hour. To this mixture was added 2-(trimethylsilyl)ethoxy-methyl chloride (Aldrich) (9.17 mL, 1.5 eq), and the resulting mixture was stirred at room temperature for 2 days. The reaction was monitored by TLC. The reaction mixture was diluted with ethyl acetate (300 mL) and water (100 mL). the organic layer was separated, washed with water (6×100 mL) and brine (1×100 mL), dried over magnesium sulfate, filtered and concentrated to give 10 g of the crude product. Purification by column chromatography using 5% ethyl acetate in hexanes afforded 4-nitro-2-(2-trimethylsilanyl-ethoxymethyl)-2H-pyrazole-3-carboxylic acid, ethyl ester (3.82 g) as a colorless oil and 4-nitro-1-(2-trimethylsilanyl-ethoxymethyl)-1H-pyrazole-3-carboxylic acid, ethyl ester (4.055 g) as a light tan oil. (M−H)+=314.

Provenance & Evidence