To a solution of 2,4-dichloropyridine (2 g, 13.51 mmol) in tetrahydrofuran (20 mL) at -78° C added LDA in THF/heptane/ethylbenzene (2M, 8.11 mL, 16.22 mmol) and the solution was stirred for 30 min. DMF (10.46 mL, 135 mmol) was added and the solution was stirred for 1 h and then warmed RT. The reaction mixture was quenched with saturated NH4Cl solution and diluted with ethyl acetate (50 mL). The organic layer was washed with saturated NaHCO3 (2*10 mL), water (20 mL), dried over Na2SO4, and concentrated under reduced pressure to afford 2,4-dichloronicotinaldehyde (2 g, 11.36 mmol, 84% yield).
