C1C(=O)N([Br:8])C(=O)C1.[CH3:9][C:10]1[CH:15]=[CH:14][C:13]([CH3:16])=[CH:12][C:11]=1[O:17][CH3:18].O.CCCCCCC>CN(C=O)C>[Br:8][C:14]1[C:13]([CH3:16])=[CH:12][C:11]([O:17][CH3:18])=[C:10]([CH3:9])[CH:15]=1A solution of NBS (306.9 g, 1.724 mol, 1.1 equiv) in DMF (850 mL) was treated dropwise with 2,5-dimethylanisole (4, 213.2 g, 220.9 mL, 1.567 mol) at 25° C. under N2. The reaction temperature was maintained under 60° C. during the addition of 2,5-dimethylanisole. The resulting reaction mixture was stirred at room temperature for an additional 1 h before being treated with H2O (2000 mL) and heptane (1000 mL). The two layers were separated and the aqueous layer was extracted with heptane (500 mL). The combined organic extracts were washed with H2O (4×800 mL), and saturated NaCl solution (500 mL), dried over MgSO4, and concentrated in vacuo. The crude product (5, 329.8 g, 336.9 g theoretical, 97.9%) was obtained as pale-yellow oil.
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