[Cl:1][C:2]1[CH:7]=[C:6]([Cl:8])[CH:5]=[CH:4][N:3]=1.C([N-]C(C)C)(C)C.[Li+].CN(C)[CH:19]=[O:20].[Cl-].[NH4+]>O1CCCC1.O.C(Cl)Cl>[Cl:1][C:2]1[C:7]([CH:19]=[O:20])=[C:6]([Cl:8])[CH:5]=[CH:4][N:3]=1Under nitrogen, a solution of 1.6 g of 2,4-dichloropyridine in 5 mL dry tetrahydrofuran (THF) was added to a solution of 6 mL of lithium diisopropyl amide in 25 mL of THF at −70° C., followed by stirring at this temperature for 3 hours. Then 1 mL of dry N,N-dimethylformamide was added at −70° C. followed by stirring at this temperature for 1 hour. Then 25 mL of saturated ammonium chloride solution was added and the reaction mixture was stirred at room temperature overnight. The reaction mixture was diluted with 25 mL of water and extracted with ethyl acetate (2×). The combine organic phases were distilled under vacuum to give solids that were dissolved in 5 mL of methylene chloride and filtered through silica gel, eluting with 100% methylene chloride. Removal of the solvent under vacuum provided the title intermediate as a solid. 1H NMR (CDCl3; 300 MHz) δ 7.41 (d, 1H, J is 5.3 Hz), 8.42 (d, 1H, J is 5.2 Hz), 10.5 (s, 1H).
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