| 96.1% |
With iodine; potassium hydroxide; In N,N-dimethyl-formamide; at 20℃; for 0.5h; |
To a solution of 5-fluoro-1H-indazole (2.0 g, 14.0 mmol) in DIVIF (50 mL) was added ‘2 (7.46 g, 28.0 mmol) and KOH (2.4 g, 42 mmol), the mixture was stirred at room temperature for 0.5 hr. The reaction was monitored by TLC. After completion, the mixture was filtered, the filtrate was concentrated in vacuum to give a residue, which was purified by a silica gel column (PE/EA = 3/1) to afford 5-fluoro-3-iodo-1H-indazole (3.7 g, yield: 96.1%) as a white solid. ‘H NIVIR (400 IVIHz, DMSO-d6): ? = 13.64 (s, 1H), 7.63 (dd, J= 4.8, 4.4 Hz, 1H), 7.38-7.30 (m, 1H), 7.20 (dd, J=6.4,2.4Hz, 1H). |
| 95.1% |
With iodine; potassium hydroxide; In N,N-dimethyl-formamide; at 20℃; for 1h; |
5-Fluoro-1H-indazole (10.00 g, 73.46 mmol) was added into N,N-dimethylformamide(80 mL), then Iodine (28.0 g, 110 mmol) and potassium hydroxide (6.20 g, 110 mmol) wereadded. After addition, the mixture was reacted for 1 hour at room temperature. The reactionmixture was poured into aqueous sodium thiosulfate solution (300 mL, 5%). The resultingmixture was extracted with ethyl acetate (100 mL x 2). The combined organic layers werewashed with water (100 mL) and saturated brine (100 mL), dried over anhydrous sodium sulfate,and filtered. The filtrate was concentrated on a rotary evaporator to give a light yellow solid(18.3 g, 95.1 %) |
| 87% |
With iodine; potassium hydroxide; In N,N-dimethyl-formamide; at 20℃; for 3h; |
General procedure: 3-Iodoindazoles were obtained by direct iodination of commercial indazoles by the method previously described by Bocchi [28] with slight modifications. A solution of 1H-indazole (3 g, 25.4 mmol), iodine (12.7 g, 50.03 mmol) and potassium hydroxide (5.34 g, 95.25 mmol)in DMF (7 mL) was stirred for 3 h at room temperature. The reaction was quenched by dilution with saturated solution of sodium bisulfite (150 mL) and a precipitated was formed. The precipitated was filtered over vacuum and washed with water (3 × 30 mL). The solid was left to dry at 30 C in a vacuum oven overnight obtaining 6.17 g of a pale yellow solid. Yield: 100%; m.p.: 136-138 C (lit.:[36] 134-136 C); IR (KBr) ν (cm-1): 3086 (NH); 424 (C-I). 1H-NMR δ (ppm): 13.50 (1H, s, H-1); 7.55(1H, d, J = 8.6 Hz, H-7); 7.45-7.40 (2H, m, H-6 and H-4); 7.19 (1H, dd, J = 7.5 Hz, H-5). 13C-NMR δ(ppm): 140.41; 127.22; 126.79; 121.23; 120.39; 110.51; 93.49; HRMS calculated for C7H5IN2: 243.9497,Found: 243.9499.3-Iodo-1H-indazole (1a). 3-Iodoindazoles were obtained by direct iodination of commercial indazoles by the method previously described by Bocchi [28] with slight modifications. A solution of 1H-indazole(3 g, 25.4 mmol), iodine (12.7 g, 50.03 mmol) and potassium hydroxide (5.34 g, 95.25 mmol) in DMF(7 mL) was stirred for 3 h at room temperature. The reaction was quenched by dilution with saturated solution of sodium bisulfite (150 mL) and a precipitated was formed. The precipitated was filtered over vacuum and washed with water (3 30 mL). The solid was left to dry at 30 C in a vacuum oven overnight obtaining 6.17 g of a pale yellow solid. Yield: 100%; m.p.: 136-138 C (lit.: [36] 134-136 C) |
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