Methyl iodide → ethyl 1-methyl-1H-pyrazole-4-carboxylate

Temperature

0 °C

A mixture of sodium hydride (3.24 g, 12.84 mmol) in tetrahydrofuran (35 mL) cooled to 0° C. was treated with a solution of 1H-pyrazole-4-carboxylic acid ethyl ester (1.5 g, 10.7 mmol) in tetrahydrofuran (10 mL). The reaction was warmed to 25° C. and was stirred at 25° C. for 1 h. At this time, the reaction was treated with methyl iodide (1.0 mL, 16.05 mmol) and then was stirred at 25° C. for 18 h. The reaction was then cooled to 0° C. and was treated with a saturated aqueous ammonium chloride solution. The resulting mixture was diluted with ethyl acetate (150 mL). This solution was washed with water (1×50 mL) and a saturated aqueous sodium chloride solution (1×50 mL), dried over magnesium sulfate, filtered, and concentrated in vacuo to afford 1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester (1.48 g, 89.7%) as a yellow oil: 1H NMR (DMSO-d6, 300 MHz) δ8.27 (s, 1H), 7.80 (s, 1H), 4.18 (q, J=7.32 Hz, 2H), 3.84 (s, 3H), 1.24 (t, J=6.96 Hz, 3H).

1. temperatureThe reaction was warmed to 25° C.
2. stirringwas stirred at 25° C. for 18 h
3. temperatureThe reaction was then cooled to 0° C.
4. washThis solution was washed with water (1×50 mL)
5. dry with materiala saturated aqueous sodium chloride solution (1×50 mL), dried over magnesium sulfate
6. filtrationfiltered
7. concentrationconcentrated in vacuo

ORD record

ord-f6b5e5696a034b4bbbcc1a9a5c38d736

Source dataset

uspto-grants-2006_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07135475B2