Example 3 Preparation of N2-(1H-indazol-5-yl)-N6-methyl-3-nitropyridine-2,6-diamine
To a reaction flask containing methanol with 40% aqueous methylamine (20 mL) was added 2-(1H-indazol-5-ylamino)-6-methoxy-3-nitropyridine (1 g) obtained by Example 1. The reaction mixture was stirred at 25°C for 1 hour. Subsequently, deionized water (20 mL) was slowly added to the reaction mixture and stirring was continued for 1 hour. After completion of the reaction, the reaction mixture was filtered and the solid product was washed with 30% aqueous methanol (5 mL). The resulting solid product was dried under vacuum at 50-60 °C to afford the target compound N2-(1H-indazol-5-yl)-N6-methyl-3-nitropyridine-2,6-diamine (0.82 g, 82% yield). Melting point: 238-240 °C. 1H-NMR (DMSO-d6, δ, ppm): 2.86 (d, 3H), 6.09 (d, 1H), 7.51 (d, 1H), 7.57 (d, 1H), 8.05 (t, 2H), 8.24 (d, 2H), 10.97 (s, 1H), 13.05 (br s, 1H).
