反应详情

温度

80 °C

To a mixture 2-[4-(2-amino-5-bromo-3-nitro-pyridin-4-yl)-piperazin-1-yl]-N-thiazol-2-yl-acetamide (0.05 g, 0.11 mmol) and ethanol (3 ml) was added benzaldehyde (15 μL, 0.29 mmol) and a freshly prepared aqueous solution of Na2S2O4 (1M; 450 μL, 0.45 mmol). The reaction mixture was stirred at 80° C. for 16 h then more benzaldehyde (15 μL, 0.29 mmol) and 1M aq. Na2S2O4 (450 μL, 0.45 mmol) were added. The reaction mixture was stirred at 80° C. for another 16 h then concentrated in vacuo. The crude product was purified by chromatography on silica gel (100% dichloromethane to dichloromethane/ethyl acetate 6:4 to dichloromethane/ethyl acetate 1:1+0.5% methanol) to give the title compound as a pale yellow solid (0.033 g, 58%); 1H-NMR (500 MHz, DMSO-d6) 2.80 (broad s, 4H, piperazine N(CH2)2), 3.42 (s, 2H, CH2), 3.72 (broad s, 4H, piperazine N(CH2)2), 7.24 (d, 1H, J=3.4 Hz, thiazole 4-H or 5-H), 7.49 (d, 1H, J=3.4 Hz, Thiazole 4-H or 5-H), 7.54 (m, 3H, Ar—H), 8.20 (dd, 2H, J=1.5, 8.0 Hz, 2,6-Ar—H), 8.25 (s, 1H, imidazo[4,5-b]pyrazine 5-H), 11.92 (broad s, 1H, NHCO), 13.54 (broad s, 1H, imidazo[4,5-b]pyrazine NH); LC-MS (ESI, m/z) Rt=5.89 min—498/500 [(M+H+), Br isotopic pattern, 100%]; ESI-HRMS: Found: 498.0716, calculated for C21H21BrN7OS (M+H+): 498.0712.

1. stirringThe reaction mixture was stirred at 80° C. for another 16 h
2. concentrationthen concentrated in vacuo
3. customThe crude product was purified by chromatography on silica gel (100% dichloromethane to dichloromethane/ethyl acetate 6:4 to dichloromethane/ethyl acetate 1:1+0.5% methanol)