A solution of N-(methoxymethyl)-N-(phenylmethyl)-N-(trimethylsilyl)methylamine (7.82 g, 32.9 mmol) in CH2Cl2 (40 mL) was added dropwise, over a 30 minutes period, to a stirred solution of (E)-4-(2,4-difluoro-phenyl)-but-3-en-2-one (4.0 g, 21.9 mmol) and trifluoroacetic acid (0.17 mL, 0.21 mmol) in CH2Cl2 (10 mL) at 0° C. The ice bath was removed, and the solution was stirred at 25° C. for an additional 48 h. It was then concentrated and purification by flash chromatography (SiO2, CH2Cl2/MeOH 98:2) afforded 6.2 g (89%) of the title compound as a yellow oil. ES-MS m/e: 316.1 (M+H+).
