Methyl iodide → 3,5-Dichloro-4-methylpyridine
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[Cl:1][C:2]1[CH:3]=[N:4][CH:5]=[C:6]([Cl:8])[CH:7]=1.[Li+].[CH3:10]C([N-]C(C)C)C.[Li]CCCC.IC.C([O-])(O)=O.[Na+]>C1COCC1.C(Cl)Cl>[Cl:1][C:2]1[CH:3]=[N:4][CH:5]=[C:6]([Cl:8])[C:7]=1[CH3:10][Cl:1][C:2]1[CH:3]=[N:4][CH:5]=[C:6]([Cl:8])[CH:7]=1.[Li+].[CH3:10]C([N-]C(C)C)C.[Li]CCCC.IC.C([O-])(O)=O.[Na+]>C1COCC1.C(Cl)Cl>[Cl:1][C:2]1[CH:3]=[N:4][CH:5]=[C:6]([Cl:8])[C:7]=1[CH3:10]
3,5-Dichloropyridine (2.04 g, 13.5 mmol) in THF (5 ml) was added dropwise to a solution of LDA [prepared from diisopropylamine (1.9 ml, 13.5 mmol) and n -BuLi (1.6M; 8.4 ml, 13.5 mmol)] in THF (25 ml) at -70° C. After stirring at this temperature for 5 min, iodomethane (0.85 ml, 13.5 mmol) was added and the reaction mixture stirred for a further 1.5h at -70° C. Saturated NaHCO3 (20 ml) and CH2Cl2 (20 ml) were added, the organic phase separated, dried (MgSO4), and concentrated in vacuo. The residue was subjected to chromatography (SiO2 ; Et2O/hexane, 1.:3) to afford the title compound (1.16 g) as a pale yellow solid. δH (CDCl3) 2.46 (3H, s, Me), and 8.36 (2H, s, pyridine H2, H6).
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