To a stirred suspension of zinc powder (0.54 g, 8.13 mmol) in THF (20 mL) was slowly added TiCl4 (0.45 mL, 4.07 mmol) via syringe at room temperature under a nitrogen atmosphere. The mixture was heated at reflux for 2 h. A solution of (4-bromophenyl)(3-fluoro-4-hydroxyphenyl)methanone (82) (0.30 g, 1.02 mmol) and 3,3,5,5-tetramethyl cyclohexanone (0.48 g, 3.05 mmol) in THF (6 mL) was added to the mixture. The reaction mixture was heated at reflux with stirring under a nitrogen atmosphere for 1 h. The reaction mixture was allowed to cool to room temperature. To the reaction mixture was slowly added 10% aqueous K2CO3 (20 mL). The reaction mixture was filtered through a pad of Celite and the pad was washed with EtOAc (100 mL). The filtrate was transferred to a separatory funnel and the layers were separated. The aqueous layer was further extracted with EtOAc (25 mL). The combined organic phase was washed with brine, dried over Na2SO4, filtered, and the filtrate was concentrated to give the crude product as yellow oil. The crude product was purified by flash chromatography on silica gel with hexanes:EtOAc (100:0 to 30:1) to give 0.33 g (78%) of compound 139 as a light yellow viscous oil. 1H NMR (400 MHz, CDCl3): δ 0.91 (s, 6H), 0.93 (s, 6H), 1.29 (s, 2H), 1.92 (s, 2H), 1.97 (s, 2H), 4.99 (d, J=3.8 Hz, 1H), 6.78-6.87 (m, 2H), 6.90 (t, J=8.6 Hz, 1H), 7.01 (d, J=8.3 Hz, 2H), 7.40 (d, J=8.4 Hz, 2H). LCMS (ES): m/z 415 (M−H)−.
