CC1C=C(C(OC)=O)C(C(OC)=O)=NC=1.BrN1C(=O)CCC1=O.N(C(C)(C)C#N)=NC(C)(C)C#N.[Br:36][CH:37](Br)[C:38]1[CH:39]=[C:40]([C:48]([O:50][CH3:51])=[O:49])[C:41]([C:44]([O:46][CH3:47])=[O:45])=[N:42][CH:43]=1>C(Cl)(Cl)(Cl)Cl>[Br:36][CH2:37][C:38]1[CH:39]=[C:40]([C:48]([O:50][CH3:51])=[O:49])[C:41]([C:44]([O:46][CH3:47])=[O:45])=[N:42][CH:43]=1A mixture of dimethyl 5-methyl-2,3-pyridinedicarboxylate (30.0 g, 0.143 mol), N-bromosuccinimide (32.0 g, 0.18 mol) and 2,2'-azobisisobutyronitrile (0.9 g, 0.0055 mol) in carbon tetrachloride (200 mL) is heated at 80° C. for 1.5 hours. Additional 2,2'-azobisisobutyronitrile (0.9 g, 0.0055 mol) is added and the reaction mixture is heated at reflux for 2 hours, cooled to room temperature and filtered. The filter cake is washed with carbon tetrachloride. The filtrate and wash are combined, washed with water and concentrated in vacuo to give an oil. The oil is shown by HPLC to contain 57% of the title product, 16% dimethyl 5-methyl-2,3-pyridinedicarboxylate and 23% dimethyl 5-dibromomethyl-2,3-pyridinedicarboxylate.
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