5-Bromo-3-phenyl-1H-indazole

885124-16-3

57639-16-4

General procedure for the synthesis of 5-bromo-3-phenyl-1H-indazole from (5-bromo-2-fluorophenyl)benzophenone: (F) Hydrazine hydrate (204 μL, 4.2 mmol) was added to a solution of intermediate XXXb (976 mg, 3.5 mmol) in anhydrous ethanol (4 mL). The reaction mixture was heated to reflux and maintained for 2 h, followed by continued stirring for 18 h at room temperature. Upon completion of the reaction, the solvent was removed by rotary evaporator. The residue was dissolved in water (appropriate amount) and ethyl acetate (EtOAc, appropriate amount) for liquid-liquid partitioning. The organic layer was separated and the aqueous layer was extracted twice with ethyl acetate (EtOAc). All organic layers were combined, dried with anhydrous sodium sulfate, filtered and concentrated. The crude product was purified by fast column chromatography to afford 5-bromo-3-phenyl-1H-indazole (Intermediate XXXf, 320 mg, 33% yield) as a white solid. Mass spectrometry analysis showed the molecular ion peak [M + H]+ = 273.