[Cl:1][C:2]1[C:3]([N+:13]([O-:15])=[O:14])=[CH:4][C:5]([CH3:12])=[C:6]([CH:11]=1)[C:7]([O:9][CH3:10])=[O:8].C1C(=O)N([Br:23])C(=O)C1>CC#N.CC(N=NC(C#N)(C)C)(C#N)C>[Br:23][CH2:12][C:5]1[CH:4]=[C:3]([N+:13]([O-:15])=[O:14])[C:2]([Cl:1])=[CH:11][C:6]=1[C:7]([O:9][CH3:10])=[O:8]A mixture of methyl 5-chloro-2-methyl-4-nitrobenzoate (862 mg, 4 mmol) and NBS (854 mg, 4.8 mmol) in MeCN (16 mL) was degassed and then AIBN (14 mg, 0.08 mmol) was added. The mixture was heated to 70° C. for 18 h. The solvent was removed in vacuo and the residue was partitioned between DCM (50 mL) and water (50 mL). The organic phase was passed through a hydrophobic frit and the solvent was removed in vacuo. Purification of the residue via silica gel column chromatography (0-100% EtOAc in iso-hexane) in order to remove baseline impurities gave methyl 2-(bromomethyl)-5-chloro-4-nitrobenzoate (1.09 g, 89%) as a brown oil. 1H NMR (400 MHz, CDCl3): δ 8.14 (s, 1H), 7.98 (s, 1H), 4.91 (s, 2H), 4.00 (s, 3H).
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