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Stage #1: 5,6-dichloro-3-iodo-1H-indazole With potassium <i>tert</i>-butylate In tetrahydrofuran at 0℃; for 0.5h;
Stage #2: methyl iodide In tetrahydrofuran at 0 - 20℃;
67.4 Step 45 ,6-Dichloro-3 -iodo- 1 -methyl- 1 H-indazole
Step 45 ,6-Dichloro-3 -iodo- 1 -methyl- 1 H-indazoleTo a solution of 5, 6-dichloro-3 -iodo- 1 H-indazole (820 mg, 2.62 mmol) in THF (8 ml) at 0°C was added KOt-Bu (412 mg, 3.67 mmol). The reaction mixture was stirred at 0°C for 30 min then added iodomethane (0.23 ml, 3.67 mmol). Stirred at 0°C for 30 min then warmed to room temperature and stirred for 1.5 hr. The reaction was quenched with water and extracted with EtOAc (2x). The combined organics were dried over MgS04 and concentrated. The crude residue was absorbed on silica gel and purified by chromatography with 20%> to 30%>EtOAc/hexanes to afford 585 mg (68%) of 5,6-dichloro-3-iodo-l-methyl-lH-indazole as a light yellow solid. 1H NMR (CDC13, 400 MHz): ? (ppm) 7.61 (s, 1H), 7.56 (s, 1H), 4.09 (s, 3H). The minor 5, 6-dichloro-3-iodo-2 -methyl- 1 H-indazole regioisomer was also observed but not isolated.
With iodine; potassium hydroxide; In N,N-dimethyl-formamide; at 20℃; for 0.75h;
Step 35 ,6 -Dichloro -3 -iodo - 1 H-indazo leTo a solution of 5, 6-dichloro-l H-indazole (0.50 g, 2.67 mmol) in DMF (8 ml) at room temperature was added powdered potassium hydroxide (450 mg, 8.02 mmol) and iodine (1.02 g, 4.01 mmol). The maroon reaction mixture was stirred at room temperature for 45 min then quenched with 10%> aqueous Na2S203 and diluted with water. The mixture was extracted with EtOAc (2x). The combined organics were washed with water (3x), dried over MgS04 and concentrated to afford 827 mg (99%) of 5,6-dichloro-3-iodo-lH-indazole as a pale yellow solid. 'H NMR (DMSO-dg, 400 MHz): ? (ppm) 13.79 (s, 1H), 7.94 (s, 1H), 7.72 (s, 1H).
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