[Synthesis]
To an oven-dried pressure tube equipped with a stirrer was added 1-(2,6-dichlorobenzyl)-1H-indazol-6-amine (18 mg, 0.044 mmol) and methanol (5 mL). Subsequently, ferric chloride hexahydrate (25 mol%, 2.6 mg), 65% hydrazine monohydrate solution (0.05 mL, 0.7 mmol) and activated charcoal (20 mg) were added, the reaction tube was sealed, and the reaction was stirred for 2 hours at 100 °C. During the reaction, a small amount of the reaction solution was taken, concentrated under reduced pressure and dissolved in a minimal amount of high-performance liquid chromatography-grade acetonitrile for LC-MS analysis to monitor the progress of the reaction. After completion of the reaction, the reaction mixture was filtered, the activated carbon and filter cake were washed with methanol (10 mL), the filtrates were combined and concentrated under reduced pressure to obtain the crude product. The crude product was mixed with silica gel and dried, then up-sampled onto a 5 g silica gel column and purified by fast column chromatography (0-20% methanol/dichloromethane gradient elution) to afford the target compound, 1-(2,6-dichlorobenzyl)-3-(pyrrolidin-1-ylmethyl)-1H-indazol-6-amine (11.5 mg, 69% yield), as a white solid. lC-MS retention time tR = 1.44 min (Method A); mass spectrum m/z = 374.95 ([M+H]+); 1H NMR (300 MHz, CDCl3) δ = 7.57 (d, J = 8.5 Hz, 1H), 7.37 (d, J = 8.2 Hz, 2H), 7.31-7.20 (s, 1H), 6.63 (d, J = 8.8 Hz, 1H), and 6.58 (s, 1H), 5.63 (s, 2H), 4.29 (s, 2H), 3.96 (br.s., 2H), 3.13 (br.s., 4H), 1.84 (br.s., 4H); 13C NMR (75 MHz, CDCl3) δ = 146.5, 142.5, 137.0, 131.6, 130.3 128.8, 121.0, 117.7, 113.7, 92.2, 52.3, 48.5, 48.2, 23.9. |