1-acetyl-1-cyclopentene 6 was dissolved in dichloromethane (22 mL) and toluene (44 mL). The resulting solution was cooled to -15^oC. Dimethylaluminum chloride (1 M in hexanes, 6.00 mL, 6.00 mmol., 20 mol%) dropwise over 5 minutes. The resulting mixture was stirred for 15 minutes, then tert-butyldimethyl(4-methylpenta-1,3-dien-2-yloxy)silane 7(6.79 g, 32.0 mol, 1.1 equiv) was slowly added in neat form. The reaction mixture was then stirred at -15^oC for 24 hours and then at 0^oC for another 24 hours. After this period, the reaction mixture was quenched with pyridine (2 mL), filtered through a short pad of silica gel eluting with diethyl ether, and concentrated in vacuo. Purification by column chromatography (EtOAc/hexane, 3:97) afforded ((3aRS, 7aSR)-6-((tert-butyldimethylsilyl)oxy)-4,4-dimethyl-2,3,3a,4,7,7a,hexahydro-1Hinden-3a-yl)ethanone 8 (6.43 g, 69%) as a clear oil which recrystallized upon standing to give long, white needles.

Glossary Terms (Show Information on Rollover): in vacuo, column chromatography, neat.