Bromine → 4-(4-bromo-1-methyl-1H-pyrazol-5-yl)pyridine

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Reaction Steps

To a 3.8:1 isomer mix of 4-(1-methyl-1H-pyrazole-5-yl)pyridine and 4-(1-methyl-1-H-pyrazole-3-yl)pyridine (0.30 g) in 5 mL chloroform cooled in ice, was added a solution of 104 μL bromine in 3 mL chloroform. After 5 h, the mixture was treated with excess saturated aqueous sodium bicarbonate and diluted with dichloromethane. The dichloromethane was washed with 3 portions of saturated aqueous sodium bicarbonate, dried over magnesium sulfate, filtered, and evaporated to yield 0.39 g crude product as a brown oil. The crude product was purified by chromatography, eluting with 15:1 ethyl acetate-methanol. Fractions containing the major component were combined to afford 0.17 g (73% yield) of a colorless oil. 1H NMR (CDCl3) was consistent with the desired structure. LC/MS indicated one major product with a M+1 molecular ion of m/z 240.3 by positive ESI.

Provenance & Evidence