[Br:1][C:2]1[CH:8]=[C:7]([CH3:9])[C:5]([NH2:6])=[C:4]([CH3:10])[CH:3]=1.C([Li])CCC.[CH3:16][Si:17](Cl)([CH3:19])[CH3:18].O>O1CCCC1>[Br:1][C:2]1[CH:8]=[C:7]([CH3:9])[C:5]([N:6]([Si:17]([CH3:19])([CH3:18])[CH3:16])[Si:17]([CH3:19])([CH3:18])[CH3:16])=[C:4]([CH3:10])[CH:3]=1To a solution of 4-bromo-2,6-dimethylaniline (commercially available) (40 g, 0.2 mol) in tetrahydrofuran (500 ml) under a nitrogen atmosphere was added a solution of n-butyl lithium in hexanes (1.6 M) (125 ml, 0.2 mol). During this operation, the internal temperature was kept between −70° C. and −78° C. After five minutes, trimethylsilyl chloride (25 ml, 0.2 mol) was added whilst the internal temperature was kept below −68° C. After five minutes, the cooling bath was replaced with a water bath and the internal temperature rose to 0° C. Then the cooling bath was put back and the reaction mixture was cooled to −78° C. To this solution, a solution of n-butyl lithium in hexanes (1.6 M) (125 ml, 0.2 mol) was added whilst keeping the internal temperature below −70° C., followed by addition of trimethylsilyl chloride (30 ml, 0.237 mol) whilst keeping the internal temperature below −68° C. The reaction mixture was gradually allowed to warm to 20° C. Hexanes (200 ml) and water (40 ml) were added and the phases were separated. The organic phase was washed with brine, dried over sodium sulfate, and concentrated. The residue was distilled under a high vacuum leading to the title compound as a colorless oil which crystallized on standing. M.p. 47-52° C. 1H-NMR (CDCl3, 400 MHz): 0.08 (s, 18H), 2.21 (s, 6H), 7.15 (s, 2H) ppm.
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