Reaction Steps
Nitrostyrene 14 (0.65 g, 2.06 mmol) was dissolved in toluene (0.6 mL) in a 2 mL sealed tube and cooled to −78° C. Butadiene was bubbled into the solution to double the volume and then the tube was sealed and heated to reflux for 48 h. To prevent bumping of the butadiene gas, the tube was cooled again to −78° C. and used directly in purification by column chromatography (SiO2; 3:1, Hex:EtOAc) to afford cyclohexene 15 (0.72 g, 1.96 mmol, 95%). 1H NMR (500 MHz, CDCl3) δ 7.40 (m, 4H), 7.36-7.28 (m, 1H), 7.06 (d, J=8.4 Hz, 1H), 6.80 (d, J=2.4 Hz, 1H), 6.56 (dd, J=8.4, 2.5 Hz, 1H), 5.86-5.77 (m, 1H), 5.71 (ddd, J=9.8, 5.1, 2.3 Hz, 1H), 5.27-5.20 (m, 1H), 5.20 (s, 2H), 5.00 (s, 2H), 3.70 (dt, J=17.0, 8.7 Hz, 1H), 3.49 (s, J=12.7 Hz, 3H), 2.84-2.74 (m, 1H), 2.71 (ddd, J=13.2, 8.4, 1.5 Hz, 1H), 2.45 (m, 2H); 13C NMR (125 MHz, CDCl3) δ 159.2, 156.1, 136.9, 129.3, 128.6, 127.0, 122.5, 120.9, 107.8, 120.6, 94.6, 85.6, 70.1, 31.5, 31.3, 29.7.
