To a stirred suspension of Zn (0.50 g, 7.59 mmol) in THF (10 mL) was added TiCl4 (0.42 mL, 3.79 mmol) dropwise. The mixture was refluxed under nitrogen for 2.5 h. Cooled to room temperature, a solution of 96 (0.245 g, 0.95 mmol) and 3,3,5,5-tetramethylcyclohexanone (0.45 g, 2.85 mmol) in THF (15 mL) was added at once. The reaction mixture was refluxed for another 2.5 h. Cooled to room temperature, the reaction was quenched with 10% K2CO3 (20 mL). The quenched 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, the layers were separated and the aqueous phase was extracted with EtOAc (50 mL). The organic extracts were combined, washed with brine and dried (Na2SO4). Concentration yielded a pale brown oil which was further purified by chromatography on a silica gel column eluted with a gradient from hexanes to 45% EtOAc:hexanes to give a a light yellow solid, Crystallization from 7:1 hexanes:EtOAc yielded 97 as colorless needles (0.15 g, 42%). mp 154-155° C. 1H NMR (400 MHz, CD3OD): δ 0.91 (s, 6H), 0.92 (s, 6H), 1.28 (s, 2H), 1.96 (s, 2H), 1.98 (s, 2H), 3.80-3.90 (m, 2H), 4.00-4.10 (m, 2H), 6.67 (d, J=8.5 Hz, 2H), 6.84 (d, J=8.6 Hz, 2H), 6.94 (d, J=8.6 Hz, 2H), 7.03 (d, J=8.6 Hz, 2H). LRMS (ESI): m/z 381 (M+H)+, 379 (M−H)−. The sample was silated prior to EI analysis. HRMS (EI) Calcd for C31H48O3Si2: 524.3142 (M+.). Found: 524.3128.
