[Br:1][C:2]1[CH:7]=[C:6]([O:8][CH2:9][CH3:10])[CH:5]=[C:4]([CH3:11])[N+:3]=1[O-].P(Cl)(Cl)Cl.O.C(#N)C>C(OCC)(=O)C>[Br:1][C:2]1[CH:7]=[C:6]([O:8][CH2:9][CH3:10])[CH:5]=[C:4]([CH3:11])[N:3]=12-Bromo-6-methyl-4-ethoxy-pyridine 1-oxide (a total of 9.85 g, 42 mmol) was divided in two batches, suspended in ethyl acetate (anhydrous, total of 130 ml), phosphorus trichloride (total of 15 ml) was added dropwise and the mixtures were stirred at 50° C. for three hours. Then the mixture of each batch was poured onto crushed ice (250 ml each) with stirring, ethyl acetate (250 ml each) was added, the phases were separated and the organic phases were washed with water (2 times), dried (magnesium sulfate) and concentrated under reduced pressure. The residues were combined and purified by column chromatography (silica, petrolether/ethyl acetate 95:5) and then by preparative HPLC (Waters XBridge, gradient of water containing 0.1% NH3 and acetonitrile) to give 2.2 g of a yellow oil (10 mmol, 24% yield).
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