反应详情

2-Chloro-4-methoxy-5-nitropyridine (Frontier Scientific, Newark, Del.; 1.02 g, 5.40 mmol) and K2CO3 (895 mg, 6.48 mmol) were purged with argon, treated with DMF (10 mL) followed by 1-methylpiperazine (0.66 mL, 5.94 mmol). The reaction mixture was then heated to 60° C. for 3 h. The reaction mixture was cooled to RT and treated with water, extracted with EtOAc (2×100 mL), washed with brine (2×25 mL) and dried over MgSO4, filtered and concentrated affording crude 1-(4-methoxy-5-nitropyridin-2-yl)-4-methylpiperazine (1.36 g, 5.39 mmol, 99% yield). m/z (ESI, +ve ion) 252.9 (M+H)+. 1H NMR (400 MHz, CDCl3) δ ppm 8.88 (1H, s), 5.97 (1H, s), 3.97 (3H, s), 3.70-3.78 (4H, m), 2.47-2.55 (4H, m), 2.36 (3H, s). Pd/C (10 wt. %, 586 mg, 0.55 mmol) and 1-(4-methoxy-5-nitropyridin-2-yl)-4-methylpiperazine (1.36 g, 5.39 mmol) were treated with EtOH (20 mL) and EtOAc (20 mL) and stirred at RT overnight (18 h) under an atmosphere of hydrogen (balloon). The reaction mixture was filtered through a pad of Celite, washed with MeOH, and concentrated to dryness affording 4-methoxy-6-(4-methylpiperazin-1-yl)pyridin-3-amine (8a) (1.22 g, 5.77 mmol, 99% yield) as a purple viscous oil. m/z (ESI, +ve ion) 223.1 (M+H)+. 1H NMR (400 MHz, CDCl3) δ ppm 7.67 (1H, s), 6.17 (1H, s), 3.87 (3H, s), 3.37-3.45 (4H, m), 3.32 (2H, br. s.), 2.51-2.60 (4H, m), 2.36 (3H, s).

1. filtrationThe reaction mixture was filtered through a pad of Celite
2. washwashed with MeOH
3. concentrationconcentrated to dryness