4-bromo-5-fluoro-1,3-dimethylpyrazole synthesis

Yield:-

Steps:

Multi-step reaction with 2 steps
1.1: n-butyllithium / tetrahydrofuran / 0.75 h / -65 °C / Inert atmosphere
1.2: 14 h / -75 - 20 °C / Inert atmosphere
2.1: N-Bromosuccinimide / acetonitrile / 12 h / 20 °C

References:

Levchenko, Vitalina;Dmytriv, Yurii V.;Tymtsunik, Andriy V.;Liubchak, Konstantin;Rudnichenko, Alexander;Melnyk, Anton V.;Veselovych, Stanislav Y.;Borodulin, Yurii V.;Otsalyuk, Oleksandr M.;Tolmachev, Andrei A.;Mykhailiuk, Pavel K. [Journal of Organic Chemistry,2018,vol. 83,# 6,p. 3265 - 3274]