To 6.25 g (50 mmol) of 4,4-dimethyl-2-cyclohexen-1-one and 0.5 g (5.6 mmol) of cuprous cyanide in 400 mL of diethyl ether at –23° under argon was added 100 mL (~0.75 M in diethyl ether) of 5-trimethylsilyl-4-pentynylmagnesium iodide during 4 hours. Methyl chloroformate (8 mL, 100 mmol) was added and stirring continued for 1 hour at –23° and 0.5 hour at room temperature. Hydrochloric acid (100 mL, 2.0 M) then was added and the organic phase separated and dried with magnesium sulfate. The solvent was removed and the residue chromatographed on silica gel using 5% diethyl ether–petroleum ether to give methyl 3,3-dimethyl-6-oxo-2-[5-(trimethylsilyl)-4-pentynyl]cyclohexanecarboxylate, 9.66 g (60%). IR 2000, 2140, 1755, 1715, 1660, 1615, 1440, 1280, 1250, 1225, 1205, and 845 cm–1; 1H NMR ( CDCl) δ 0.13 (s, 9H), 0.93 (s, 3H), 1.02 (s, 3H), 1.2–2.3 (m, 11H), 3.74 (s, 3H). Anal. Calc. for CHOSi: C, 67.05; H, 9.4. Found: C, 67.1; H, 9.65.