[Cl:1][C:2]1[C:7]([C:8]([OH:10])=[O:9])=[C:6]([CH3:11])[CH:5]=[C:4]([Cl:12])[N:3]=1.C(=O)([O-])[O-].[K+].[K+].[CH2:19](I)[CH3:20].O>CN(C)C=O>[CH2:19]([O:9][C:8]([C:7]1[C:2]([Cl:1])=[N:3][C:4]([Cl:12])=[CH:5][C:6]=1[CH3:11])=[O:10])[CH3:20]
A mixture of 2,6-dichlor-4-methylpyridin-3-carboxylic acid (100 g, 485 mmol) and potassium carbonate (100 g, 728 mmol) in dimethylformamide (1.25 I) is stirred for 30 h at RT before ethyl iodide (59.5 ml, 728 mmol) is added and stirring is continued for 18 h. After completion of the reaction, water is added and the mixture is extracted with ethyl acetate (3×). The combined organic layers are washed with water (2×) and brine (1×), dried over magnesium sulphate and evaporated to dryness to yield 2,6-dichloro-4-methyl-pyridine-3-carboxylic acid ethyl ester (112 g), which was used without further purification.
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