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With pyridine; dmap; hydrazine; at 100.0℃; for 24.0h;
Intermediate 2; 3-bromo-7-(trifluoromethyl)-lH-indazole; Step A: 7-(trifluoromethyl)-lH-indazole[0169] ; A solution of 2-fluoro-3-trifluoromethylbenzaldehyde (5 g, 26 mmol)), hydrazine hydrate (8.3 mL, 260 mmol) and DMAP (3.17 g, 26 mmol.) in 10 mL pyridine was heated at 100 0C for 24 hours. The cool reaction mixture was partitioned with EtOAc and 1 N HCl. The organic phase was washed with brine and dried with anhydrous sodium sulfate (Na2SO4). The organic phase was concentrated in vacuo to give 4.5 g of product. The crude product was recrystallized from Et2O/ hexane to give the title compound (3.6 g, white solid, mp 90C). 1H NMR (DMSO- d6):delta 7.27 (t, IH), 7.73 (d, IH), 8.10 (d, IH), 8.29 (d, IH), 13.63 (s, IH) MS (ESI) m/z 185 [M-H]"
With sodium hydroxide; bromine; In water; at 20.0℃; for 2.0h;
Step B: 3-bromo-7-(trifluoromethyl)-lH-indazole[0170] ; To a mechanically stirred solution of 7-trifluoromethyl-indazole (3.5 g,18.8 mmol) in 20% NaOH was added bromine (0.62 mL, 12.1 mmol) dropwise. After stirring at ambient temperature for 2 hours, the reaction mixture was cooled and acidified to pH 6-7 by careful addition of concentrated HCl. The solids formed were filtered and dried to give the title compound (2.9 g) as a white solid. 1H NMR (DMSO-d6): delta 7.39 (t, IH), 7.86 (d, IH), 7.91(d, IH), 14.02 (s, IH). EPO <DP n="51"/>MS (ESI) m/z 263 ([M-H]").
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