反应详情

3-Bromo-2-chloro-5-nitropyridine (119 g, 0.500 mol, prepared according to V. Koch and S. Schnatterer, Synthesis, 1990, 497-498), potassium fluoride (79.5 g, 1.37 mol), and tetraphenylphosphonium bromide (109 g, 0.260 mol) were combined in acetonitrile (1.5 L) and heated at reflux for 4 days until GLC indicated complete consumption of the 3-bromo-2-chloro-5-nitropyridine. The volume of the mixture was reduced to 750 mL in vacuo then and diluted with 2 L of ether. The mixture was filtered and the filtrate concentrated. The residue was triturated with hot hexane (2×1 L then 2×0.5 L) and the combined hexane extracts were concentrated to give 62.8 g (54%) of the title compound: 1H NMR (DMSO-d6 300 MHz) δ 9.14 (m, 2H).

1. temperatureheated
2. temperatureat reflux for 4 days until GLC
3. customconsumption of the 3-bromo-2-chloro-5-nitropyridine
4. additiondiluted with 2 L of ether
5. filtrationThe mixture was filtered
6. concentrationthe filtrate concentrated
7. customThe residue was triturated with hot hexane (2×1 L
8. concentration2×0.5 L) and the combined hexane extracts were concentrated