Hydrazine → 6-Bromo-1H-indazole

Participants

Reaction Conditions

Reaction Steps

To a 100 mL round-bottomed flask was added hydrazine (30 mL, 832 mmol) and 4-bromo-2-fluorobenzaldehyde (4.69 g, 23 mmol). The solution was stirred at 125° C. for 3 hours. After cooling to ambient temperature, the solution was concentrated under reduced pressure. The solution was quenched by pouring it into a mixture of ice water (100 mL), and then extracting with EtOAc (3×100 mL). The organic layers were combined, dried over sodium sulfate, and filtered. The solution was evaporated to dryness, and adsorbed onto silica gel. The crude product was purified using column chromatography through a Redi-Sep® pre-packed silica gel column (40 g), eluting with a gradient of 0% to 100% EtOAc in hexanes, to provide 6-bromo-1H-indazole (4.6 g, 18 mmol, 76% yield). LCMS (M+H) 197.9 calc. for C7H5BrN2 197.0, 1H NMR (400 MHz, CD3OD): δ ppm 8.03 (s, 1H), 7.67-7.72 (2H, m), 7.24-7.26 (m, 1H).

Provenance & Evidence