6-Vinyl-1,4-dioxaspiro[4.5]dec-6-ene(7). Trimethylsilyl triflate (0.58 mL, 3.2 mmol) was added dropwise to a solution of 2-
iodocyclohex-2-enone21 (14.2 g, 64 mmol) and bis(trimethylsilylethers)22 (19.8 g, 96 mmol) in CH2Cl2 (150 mL) at −40 °C. The reaction was allowed to warm to 0 °C over 1 h and was stirred for 26 h at this temperature.