[Li][CH2:2]CCC.[Br:6][C:7]1[CH:8]=[C:9]([C:15]([CH3:19])([CH3:18])[CH:16]=O)[CH:10]=[CH:11][C:12]=1[O:13][CH3:14]>[Br-].C[P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.C1COCC1>[Br:6][C:7]1[CH:8]=[C:9]([C:15]([CH3:19])([CH3:18])[CH:16]=[CH2:2])[CH:10]=[CH:11][C:12]=1[O:13][CH3:14]A suspension of methyltriphenylphosphonium bromide (7.71 g, 0.0215 mol) in dry THF (100 mL) was cooled to 0° C. under argon. n-BuLi (2.5M, 8 mL, 0.020 mol) was added slowly. The resulting clear orange solution of the ylide was stirred for another 15 min at 0° C. 2-(3-Bromo-4-methoxy-phenyl)-2-methyl-propionaldehyde (3.7 g, 0.014 mol) was dissolved in dry THF (50 mL) and added to ylide-solution. The mixture was stirred for 3 h/25° C. and the resulting suspension was quenched with MeOH (10 mL). The solvent was removed under reduced pressure and the crude product was purified by flash chromatography using n-heptane as eluent. Yield: 3.1 g (84%). GCMS: >99%
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