[Synthesis]
General procedure for the synthesis of 5-chloro-1H-indazole-3-carboxamide from 5-chloro-1H-indazole-3-carboxylic acid: 5-chloro-1H-indazole-3-carboxylic acid (0.8 g, 4.0 mmol) was dissolved in anhydrous THF (20 mL), followed by the sequential addition of isobutyl chloroformate (0.64 mL, 4.9 mmol) and N-methylmorpholine (0.7 mL, 6.1 mmol). The reaction mixture was stirred at 0 °C for 2 h under argon protection. Then, 10 mL of ammonia solution was slowly added to the reaction system and stirring was continued at 25 °C for 1 hour. Upon completion of the reaction, the THF solvent was removed by distillation under reduced pressure. The resulting solid was filtered through a Brinell's funnel and washed with ether and finally dried under vacuum to give a light-colored solid 5-chloro-1H-indazole-3-carboxamide (0.5 g, 63% yield). The product characterization data were as follows: IR (thin film method, cm^-1 ): 2925, 2854, 1463; ^1H NMR (200 MHz, DMSO-d6): δ 8.14 (d, J = X Hz, 1H), 7.80 (br s, 1H), 7.66 (d, J = 8.9 Hz, 1H), 7.45-7.39 (m, 2H); MS ( ESI): m/z 218 ([M + Na]+). |