Nitric Acid → 7-Bromo-2-ethyl-3-nitropyrazolo[1,5-a]pyridine

Participants

Reaction Conditions

Reaction Steps

Fuming nitric acid (1.7 mL) was added dropwise to a solution of 7-bromo-2-ethylpyrazolo[1,5-a]pyridine (6.9 g, 34.2 mmol) in concentrated sulfuric acid (13.8 mL) at an internal temperature of below 30° C. while cooling with ice. After stirring the reaction mixture for 30 minutes, it was added to ice water (138 mL) and the precipitate was filtered out. The obtained precipitate was added ethyl acetate (226 mL) and methanol (38 mL), and the mixture was heated to 70° C., and then the precipitate was collected by filtration while cooling with ice. The solvent of the obtained filtrate was evaporated under reduced pressure, and the concentrated residue was recrystallized from heptane-ethyl acetate (1:1) to afford 2.4 g of the title compound as light brown crystals (31% yield).

Provenance & Evidence