Sodium Carbonate → 4-Bromo-1-(1,1-dimethylethyl)-1H-pyrazole

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Reaction Steps

To a suspension of Na2CO3 (36 g, 339 mmol) in CH2Cl2 (300 mL) was added 1-t-butyl-1H-pyrazole from Example B19 (21 g, 170 mmol) and Br2 (9 mL), and the resulting mixture was stirred at RT overnight. The solid was removed by filtration and the filter cake was washed with CH2Cl2. The filtrates were washed with water and brine, dried (MgSO4), and concentrated to give crude 4-bromo-1-t-butyl-1H-pyrazole (29 g, 85%), used without further purification. 1H NMR (300 MHz, CDCl3): δ 7.49 (s, 1 H), 7.45 (s, 1 H), 1.53 (s, 9 H); MS (ESI) m/z: 203 [M+H]+.

Provenance & Evidence