反应详情

To a solution of 2-amino-4-chloropyridine (5.00 g, 0.0389 mol) in sulfuric acid (40.8 mL) with stirring at 0° C. was added a solution of nitric acid (2.72 g, 0.0389 mol) and sulfuric acid (3.89 g, 0.0389 mol). The mixture was stirred (1 hr) then poured into 200 g ice and 100 ml water. The solid was filtered and collected. The solution was neutralized with 28% NH3 in water to pH ˜5. The solution was extracted with EtOAc (3×300 ml). The solid also was dissolved in EtOAc and neutralized with 28% NH3 in H2O. The organic layers were combined, concentrated with 30 g silica gel, and purified by flash chromatography (20 to 60% EtOAc/hexanes) to afford the title compound (2.40 g, 36%) as a yellow solid.

1. filtrationThe solid was filtered
2. customcollected
3. extractionThe solution was extracted with EtOAc (3×300 ml)
4. dissolutionThe solid also was dissolved in EtOAc and neutralized with 28% NH3 in H2O
5. concentrationconcentrated with 30 g silica gel
6. custompurified by flash chromatography (20 to 60% EtOAc/hexanes)