4-Bromo-1-(2-fluorophenyl)-1H-pyrazole synthesis

Yield:957062-81-6 46%

Reaction Conditions:

with bromine;acetic acid at 0 - 20; for 16 h;

Steps:

13 Example 13 Synthesis of Compound Intermediate 13.

To solution of 1-(2-fluorophenyl)-1H-pyrazole in acetic acid (5 mL) was added No.38 bromine (3 g, 18.5 mmol) in acetic acid (10 mL) at 0°C. The reaction mixture was stirred at room temperature for 16 h. The reaction mixture was cooled to room temperature, poured into ice and H2O in a 100 mL beaker and excess saturated, No.39 aqueous NaHCO3 was added until all the acetic acid had been quenched. No.40 Ethyl acetate (50 mL) was added and the layers were separated. The aqueous layer was extracted with ethyl acetate twice and the combined organics were dried over Na2SO4 and concentrated in vacuo to give a crude solid which was purified by flash column chromatography (SiO2, 1:1 hexanes-ethyl acetate) to give No.41 4-bromo-1-(2-fluorophenyl)-1H-pyrazole (2 g, 46% yield). LC/MS APCI: Calculated Observed m/z [M+H]+ 241.2. 1H-NMR 400 MHz, DMSO-d6: δ 8.48 (s, 1H), 7.94 (s, 1H), 7.64 (t, J=8.00 Hz, 1H), 7.52-7.47 (m, 2H), 7.39-7.36 (m, 1H).

References:

US2020/131154,2020,A1 Location in patent:Paragraph 0213-0215