3-Bromo-2-chloro-5-nitropyridine → 3-Bromo-2-fluoro-5-nitropyridine

Beteiligte Stoffe

Reaktionsschritte

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 the residual liquid was diluted with 2 L of ether. The mixture was filtered and the filtrate concentrated. The residue was triturated with hot hexane, 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).

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