Methyl iodide → 5-Bromo-1-methyl-1H-indazole

Reaction equation

[Br:1][C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][CH:10]=1)[NH:7][N:6]=[CH:5]2.[C:11](=O)([O-])[O-].[Cs+].[Cs+].IC>CN(C)C=O>[Br:1][C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][CH:10]=1)[N:7]([CH3:11])[N:6]=[CH:5]2

Participants

Procedure

A suspension of 5-bromo-1H-indazole (200 mg, 1.02 mmol), cesium carbonate (661 mg, 2.00 mmol), and iodomethane (156 mg, 1.10 mmol) in dimethylformamide (3 mL) was stirred at room temperature for 15 h. The mixture was partitioned between 5% lithium chloride and ethyl acetate, the aqueous layer was extracted with ethyl acetate (2×), the combined organic extracts were washed with 1 N sodium hydroxide, and brine, dried over anhydrous sodium sulfate, filtered and concentrated. Column chromatography on silica (hexanes/ethyl acetate 4:1) gave 5-bromo-1-methyl-1H-indazole (150 mg, 70% yield) as an orange solid. MS (EI) for C8H7BrN2: 212 (MH+).