反応手順
To a mixture of 6′-bromo-4-methoxyspiro[cyclohexane-1,2′-inden]-1′(3′H)-one (3) (0.9822 g, 3.18 mmol, 1.0 equiv) and 2-(trimethylsilyl)ethanesulfonamide) (SESNH2)(0.6338 g, 3.50 mmol, 1.1 equiv) in C1CH2CH2Cl (10 mL), cooled to 0° C., were successively added Et3N (0.9 mL, 6.46 mmol, 2.0 equiv) and TiCl4 (1.0 M in CH2Cl2, 3.4 mL, 3.4 mmol, 1.1 equiv). After 10 min, the ice bath was removed. The reaction mixture was stirred at room temperature for 3 h and then heated at 110° C. for 42 h. The reaction mixture was cooled to room temperature, quenched with water, and extracted with CH2Cl2. The combined organic phase was dried (Na2SO4) and evaporated. The residue was purified by chromatography on silica gel eluted with hexanes/ethyl acetate to afford 1.3685 g (91%) of N-(5′-bromo-4-methoxyspiro[cyclohexane-1,2′-indene]-3′(1′H)-ylidene)-2-(trimethylsilyl)ethanesulfonamide (8) as a solid. LC-MS tR=2.31 min in 3 min chromatography, m/z 472, 474 (MH+); 1H NMR (400 MHz, CDCl3) δ 8.78 (br s, 1H), 7.67 (dd, J=8.2, 1.8 Hz, 1H), 7.29 (d, J=8.2 Hz, 1H), 3.39 (s, 3H), 3.29-3.21 (m, 3H), 2.98 (s, 2H), 2.16-2.12 (m, 2H), 1.80-1.76 (m, 2H), 1.62-1.57 (m, 2H), 1.42-1.33 (m, 2H), 1.21-1.17 (m, 2H), 0.10 (s, 9H); 13C NMR (100 MHz, CDCl3) δ 189.97, 151.30, 137.91, 133.35, 127.50, 121.43, 78.10, 55.80, 51.79, 51.39, 39.55, 33.97, 28.60, 9.98, −1.93.
