反应详情

To a solution of titanium tetrachloride (0.015 mol, 2.8 g) in tetrahydrofuran (50 mL) was added lithium aluminum hydride (0.0175 mol, 0.7 g). The black slurry was stirred 15 min before adding methyl 6-bromo-3-chloro-4-nitropyridine-2-carboxylate, N-oxide (0.007 mol, 2.3 g) in THF (25 mL). The solution was stirred 1 hr before pouring into 1:1 H2O/NH4OH and filtering. The filtrate was extracted with EtOAc (2×75 mL). The organic phase was dried (Na2SO4), and concentrated. The red solid was chromatographed over silica in 4:1 EtOAc/hexane to give methyl 4-amino-6-bromo-3-chloropyridine-2-carboxylate (0.003 mol, 0.8 g); mp 194-5° C. 1H NMR(CDCl3): δ 3.95 (3H, s), 5.3 (2H, bs), 6.9 (1H, s).

1. stirringThe solution was stirred 1 hr
2. filtrationfiltering
3. extractionThe filtrate was extracted with EtOAc (2×75 mL)
4. dry with materialThe organic phase was dried (Na2SO4)
5. concentrationconcentrated
6. customThe red solid was chromatographed over silica in 4:1 EtOAc/hexane