[Synthesis]
The general procedure for the synthesis of tert-butyl 3-iodo-7-methoxy-1H-indazole-1-carboxylate from 3-iodo-7-methoxy-1H-indazole and di-tert-butyl dicarbonate was as follows: 3-iodo-7-methoxy-1H-indazole (1.33 g, 4.86 mmol) was dissolved in acetonitrile (20 mL), and sequentially added di-tert-butyl dicarbonate (1.34 mL, 5.83 mmol), triethylamine (0.81 mL, 5.81 mmol) and N,N-dimethylaminopyridine (60.0 mg, 0.491 mmol). The reaction mixture was stirred at room temperature for 3 hours. After completion of the reaction, water was added to the reaction solution and extracted with ethyl acetate. The organic layer was washed with saturated brine and dried over anhydrous magnesium sulfate. The solvent was removed by concentration under reduced pressure, and the crude product was purified by silica gel column chromatography (eluent: hexane/ethyl acetate=5/1) to afford tert-butyl 3-iodo-7-methoxy-1H-indazole-1-carboxylate (1.79 g, 98% yield).1H-NMR (CDCl3) δ: 1.68 (9H, s), 3.99 (3H, s), 7.01 (1H, d, J =7.8 Hz), 7.10 (1H, dd, J=8.0,0.7 Hz), 7.30 (1H, dd, J=8.0,7.8 Hz). |