Stannous chloride dihydrate → 5-Bromo-6-fluoropyridin-3-amine

関与物質

反応手順

To a solution of 3-bromo-2-fluoro-5-nitropyridine from step 131a above (5.0 g, 23 mmol) in MeOH (100 mL) was added tin(II) chloride dihydrate. The mixture was heated at reflux for 3 hours, then cooled to ambient temperature and concentrated in vacuo. The residue was diluted with saturated aqueous NaHCO3 and EtOAc resulting in formation of an emulsion which was filtered. The filtrate was poured into a separatory funnel and the layers were separated. The aqueous phase was extracted with EtOAc (2×). The combined organic extracts were washed with brine, dried (MgSO4), and concentrated. Purification by chromatography (silica gel; hexane/EtOAc, 70:30) afforded 3.61 g (83%) of the title compound as a yellow solid: mp 91-92° C.; 1H NMR (CDCl3, 300 MHz) δ 7.15 (dd, J=2.5, 7.5 Hz, 1H), (dd, J=2.0, 2.5 Hz, 1H); MS (CI/NH3) m/z 191, 193 (M+H)+ 208, 210 (M+NH4)+.

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