24424-99-5

66607-27-0

290368-00-2

1. 3-Iodo-1H-indazole (0.2 g, 0.82 mmol), di-tert-butyl dicarbonate (0.2 g, 0.92 mmol) and triethylamine (1 mL) were mixed and placed under ultrasonic radiation for 10 minutes. 2. After completion of the reaction, the reaction mixture was neutralized with 1 M HCl solution. 3. The neutralized solution was extracted using dichloromethane (3 x 30 mL). 4. The organic layers were combined and dried over anhydrous sodium sulfate. 5. Vacuum remove the solvent to give the pure product 3-iodo-1H-indazole-1-carboxylic acid tert-butyl ester as light yellow crystals. Yield: 100%; Melting point: 93-95°C; IR (KBr) ν (cm^-1): 1728 (C=O); 1150 (C-O); 424 (C-I). 1H-NMR (CDCl3) δ (ppm): 8.09 (1H, d, J=8.5 Hz, H-7); 7.55 (1H, t, J=7.8 Hz, H-4); 7.46 (1H, d, J=7.9 Hz, H-6); 7.33 (1H, t, J=7.6 Hz, H-5); 1.71 (9H, s, CH3). 13C-NMR (CDCl3) δ (ppm): 148.35; 139.59; 130.17; 129.98; 124.21; 121.96; 114.56; 102.95; 85.48; 28.18. HRMS (ESI) m/z calculated value C12H13IN2O2 [M+H]+: 344.0022, measured value: 344.0016. For the synthesis of tert-butyl 3-iodo-5-nitro-1H-indazole-1-carboxylate (2b): 1. 3-iodo-5-nitro-1H-indazole (0.2 g, 0.69 mmol), di-tert-butyl dicarbonate (0.17 g, 0.78 mmol) and triethylamine (1 mL) were used as raw materials, and the same procedure as above was followed. 2. 0.27 g of pure product as a pale yellow solid was obtained. Yield: 100%; Melting point: 144-145 °C; IR (KBr) ν (cm^-1): 1744 (C=O); 1528 (NO2).