[OH:1][C:2]1[CH:7]=[CH:6][C:5]([N+:8]([O-:10])=[O:9])=[CH:4][N:3]=1.Cl[C:12]([F:17])([F:16])C([O-])=O.[Na+]>C(#N)C>[F:16][CH:12]([F:17])[O:1][C:2]1[CH:7]=[CH:6][C:5]([N+:8]([O-:10])=[O:9])=[CH:4][N:3]=1.[F:16][CH:12]([F:17])[N:3]1[CH:4]=[C:5]([N+:8]([O-:10])=[O:9])[CH:6]=[CH:7][C:2]1=[O:1]2-Hydroxy-5-nitro-pyridine (5 g) was treated with sodium chlorodifluoro-acetate (11.5 g) in refluxing acetonitrile (186 ml) for 2 days. The solvent was evaporated, the residue poured into ethyl acetate, washed with brine, dried over sodium sulfate and then concentrated in vacuo. Chromatography on silica gel (eluent: hexane/ethyl acetate 1:1) afforded 2-difluoromethoxy-5-nitro-pyridine (1 g, 15%) and 1-difluoromethyl-5-nitro-1H-pyridin-2-one (90 mg, 1.5%). 2-Difluoromethoxy-5-nitro-pyridine: MS (ES+) 191 (MH+); 1H NMR (400 MHz, CDCl3) 7.05 (d, 1H), 7.51 (t, 1H), 8.53 (dd, 1H), 9.09 (d, 1H). 1-Difluoromethyl-5-nitro-1H-pyridin-2-one: MS (ES+) 191 (MH+); 6.65 (d, 1H), 7.63 (t, 1H), 8.14 (dd, 1H), 8.73 (d, 1H).
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