4-[(2-bromophenyl)sulfonyl]benzaldehyde (Step 4, 3.4 g, 10 46 mmol), dimethyl (2,4-difluorobenzyl)phosphonate (2.36 g, 11.51 mmol) and 15-crown-5 (0.23 mL, 1.15 mmol) were dissolved in tetrahydrofuran (21 mL) under nitrogen and cooled to 0° C. Sodium hydride (276 mg) was added and the reaction allowed to warm slowly to room temperature. Saturated sodium carbonate solution and ethyl acetate were added. The organic layer was washed with brine, dried over Na2SO4 and evaporated in vacuo. The residue was purified by flash column chromatography on silica, eluting with 35% ethyl acetate/isohexane, to give 1-((E)-2-{4-[(2-bromophenyl)sulfonyl]phenyl}vinyl)-2,4-difluorobenzene as a white solid (3.1 g, 69%). δH (400 MHz, d6 DMSO): 8.33 (1H, dd, J=1.7, 7.9 Hz), 7.89-7.81 (6H, m), 7.72 (1H, td, J=1.2, 7.6 Hz), 7.62 (1H, td, J=1.8, 7.6 Hz), 7.45-7.35 (2H, m), 7.33-7.29 (1H, m), 7.16 (1H, td, J=2.5, 8.3 Hz).
