反应详情

温度

55 °C

To a 50 ml round-bottomed flask containing 2-amino-4,5-dichloropyridine (0.275 g, 1.65 mmol) and cooled into an ice-bath was added conc. H2SO4 (2.79 g). The reaction mixture was stirred for 3 min and then HNO3 (70%; 0.186 g) was dropwise added. The reaction mixture was stirred at 0° C. (ice-bath) for 7 min, then heated to 55° C. and stirred at this temperature for 1 h, allowed to cool to room temperature, diluted with ice-water (˜15 ml) and the pH was adjusted to ˜7.5 with 10% aqueous NaOH. The yellow precipitate was collected by filtration, washed with water and dried in vacuo over P2O5, then absorbed on silica gel and the free running powder was placed on a 10 g isolute silica column. Elution with 2% ethyl acetate in dichloromethane afforded the title compound as a yellow solid (0.090 g, 26%); 1H-NMR (250 Mz, DMSO-d6) 7.39 (s, 2H, NH2), 8.39 (s, 1H, 6-H); LC-MS (ESI, m/z) 6.54 min—208, 210, 212 [(M+H)+, Cl2 isotopic pattern].

1. temperaturecooled into an ice-bath
2. stirringThe reaction mixture was stirred at 0° C. (ice-bath) for 7 min
3. stirringstirred at this temperature for 1 h
4. temperatureto cool to room temperature
5. filtrationThe yellow precipitate was collected by filtration
6. washwashed with water
7. dry with materialdried in vacuo over P2O5
8. customabsorbed on silica gel
9. washElution with 2% ethyl acetate in dichloromethane