[Br:1][C:2]1[CH:10]=[C:9]2[C:5]([CH:6]=[N:7][NH:8]2)=[C:4]([CH3:11])[CH:3]=1.[OH-].[Na+].[CH2:14](I)[CH3:15]>C1COCC1.S([O-])(O)(=O)=O.C([N+](CCCC)(CCCC)CCCC)CCC>[Br:1][C:2]1[CH:10]=[C:9]2[C:5]([CH:6]=[N:7][N:8]2[CH2:14][CH3:15])=[C:4]([CH3:11])[CH:3]=1To a solution of 6-bromo-4-methyl-1H-indazole (1000 mg, 4.7 mmol) in THF (15 mL) was added sodium hydroxide (474 mg, 11.8 mmol) and tetrabutylammonium hydrogen sulfate (80.5 mg, 0.24 mmol). The reaction mixture was stirred at r.t. for 1 h and then treated with ethyl iodide (887 mg, 5.7 mmol) dropwise. The resulting mixture was stirred at r.t. overnight. The mixture was concentrated under reduced pressure and the residue was purified by silica gel column chromatography (0-100% EtOAc in heptane) to afford 6-Bromo-1-ethyl-4-methyl-1H-indazole (476 mg, 42%). 1H NMR (600 MHz, CDCl3) δ 1.51 (t, 3H), 2.57 (s, 3H), 4.38 (q, 2H), 7.04-7.06 (m, 1H), 7.43 (s, 1H), 7.97 (d, 1H). MS (AP+)(M+H) 239.
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