[CH3:1][O:2][C:3]([C:5]1[C:6]([Cl:13])=[N:7][C:8]([Cl:12])=[CH:9][C:10]=1[CH3:11])=[O:4].[Br:14]N1C(=O)CCC1=O.CC(N=NC(C#N)(C)C)(C#N)C.C(O)(=O)C>C(Cl)(Cl)(Cl)Cl>[CH3:1][O:2][C:3]([C:5]1[C:6]([Cl:13])=[N:7][C:8]([Cl:12])=[CH:9][C:10]=1[CH2:11][Br:14])=[O:4]
To a solution of 5.3 g (24.1 mmol) 2,6-dichloro-4-methyl-pyridine-3-carboxylic acid methylester in CCl4 (92 ml) were added 3.1 g (26.5 mmol) N-Bromosuccinimide, 395 mg (2.4 mmol) AIBN and 1.45 ml (25.3 mmol) acetic acid. The mixture was irradiated with a 200 W Wolfram lamp at 60° C. for 24 h. Subsequently the mixture was filtered through celite and the filtrate was concentrated in vacuo. Purification of the residue by CC (hexane/EtOAc 97:3) provided 5.2 g of a mixture of 2,6-dichloro-4-methyl-pyridine-3-carboxylic acid methylester and 4-(bromomethyl)-2,6-dichloro-pyridine-3-carboxylic acid methylester which was used in subsequent reactions without further purification.
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