[NH2:1][C:2]1[C:7]([Cl:8])=[CH:6][C:5]([Br:9])=[CH:4][C:3]=1[C:10](=O)[CH2:11][CH3:12].[N:14]([O-])=O.[Na+].Cl[Sn]Cl>OS(O)(=O)=O.O>[Br:9][C:5]1[CH:4]=[C:3]2[C:2](=[C:7]([Cl:8])[CH:6]=1)[NH:1][N:14]=[C:10]2[CH2:11][CH3:12]1-(2-Amino-5-bromo-3-chloro-phenyl)-propan-1-one (130.0 mg, 0.50 mmol) dissolved in aqueous 50% H2SO4 (2.5 mL) and NaNO2 (43.1 mg, 0.59 mmol) was slowly added to this mixture at 0° C. The mixture was then stirred at room temperature for 1 hour. SnCl2 2H2O (342.0 mg, 1.48 mmol) was then added, and the mixture was stirred at 0° C. for 1 hour, and then diluted with water. White solid appeared and was collected by filtration and dried to afford 5-bromo-7-chloro-3-ethyl-1H-indazole as a solid (127.0 mg, 98.8%).
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