Potassium tert-butoxide → HCID 59227486, Verbindung

(3-Cyclohexenylprop-2-ynyloxy)dimethylsilane (2.77 g, 14.25 mmol) and KOtBu (0.160 g, 1.425 mmol) were used according to the general procedure. The brown oily crude reaction mixture was purified by flash chromatography using hexanes/Et2O (6:1) as eluant to produce 10e as a clear colorless oil (1.437 g, 7.394 mmol, 51.9%), which was used in Diels-Alder reactions without further purification. Analytical samples were prepared from this chromatographic compound (0.235 g, 1.209 mmol) by using a chromatotron (2.0 mm, silica gel) yielded the title compound as a colorless clear liquid in pure form (0.167 g, 0.859 mmol, 71.1%): Rf 0.34 (hexanes/Et2O, 8:1); 1H NMR (300 MHz, CDCl3) δ 6.49 (s, 1H, H-4), 5.61 (s, 1H, H-8), 4.64 (s, 1H, H-5), 2.04-2.26 (m, 4H, H-9, 12), 1.51-1.77 (m, 4H, H-10, 11), 0.32 (s, 6H, H-6); 13C NMR (300 MHz, CDCl3) δ 142.6 (C-3), 136.9 (C-4), 135.2 (C-7), 128.8 (C-8), 72.0 (C-5), 26.1 (C-9, 12), 22.6 (C-10/11), 22.4 (C-10/11), 0.74 (C-6); HRMS calcd for C11H18OSi (M+) 194.1127. found 194.1121.