Hydrochloric Acid → 5-Bromo-3-chloro-2-methylpyridine
Reaktionsgleichung
[Br:1][C:2]1[CH:3]=[C:4]([Cl:19])[C:5]([CH:8](C(OCC)=O)C(OCC)=O)=[N:6][CH:7]=1.Cl>>[Br:1][C:2]1[CH:3]=[C:4]([Cl:19])[C:5]([CH3:8])=[N:6][CH:7]=1Komponenten
3
Versuchsvorschrift
A solution of impure diethyl 2-(5-bromo-3-chloropyridin-2-yl)malonate (Intermediate 42, 0.41 g, 1.2 mmol) and conc. aq. HCl (3 mL) was heated at reflux for 3 h. The volatiles were removed in vacuo, and the residue was co-evaporated with acetonitrile. The residual solid (mono-decarboxylated acid) was dissolved in dioxane (4.5 mL) and heated at reflux overnight. The volatiles were removed in vacuo. The residue was purified by flash chromatography (4 g SiO2, heptane/EtOAc gradient) affording the title compound (0.12 g, 51% yield): 1H NMR (500 MHz, CDCl3) δ ppm 2.60 (s, 3 H), 7.82 (d, 1 H), 8.46 (d, 1 H); MS (CI) m/z 206 [M+H]+.