Hydrazine → 6-Bromo-1H-indazole

Participants

Reaction Steps

A solution of 2-fluoro-4-bromobenzaldehyde (5.09 g, 25 mmol) was dissolved in glyme (25 mL) and slowly treated over 10 minutes with anhydrous hydrazine (25 mL, 0.8 mol, 32 eq.). The resulting biphasic mixture was then held at reflux overnight. The reflux condenser was replaced with a short-path distillation head and about half the solvent distilled, at which time the reaction flask showed one phase and two phases were evident in the distillate. The undistilled residue was cooled and treated with water (25 mL), forming a white precipitate. This solid was collected by filtration, washed thoroughly with water, and dried in vacuo to give 6-bromoindazole (4.21 g, 85%) as white crystals.

Provenance & Evidence