“…The solvent was removed in vacuo to obtain a crude oil, which was then purified by flash column chromatography (4:1 petroleum ether/EtOAc) to afford the title product 12 as pale yellow oil (4.00 g, 77%). R f : 0.46 (4:1 petroleum ether/EtOAc); [α] D : −59.1 ( c 0.20, CHCl 3 ) [lit . [α] D : −64.0 ( c 1.00, CHCl 3 )]; 1 H NMR (CDCl 3 , 400 MHz): δ 7.36–7.20 (m, 5H), 5.94–5.83 (m, 1H), 5.14–5.02 (m, 2H), 4.71–4.65 (m, 1H), 4.22–4.16 (m, 2H), 3.30 (dd, 1H, J = 13.4, 3.3 Hz), 3.10 (dt, 1H, J = 16.6, 7.7 Hz), 3.01 (dt, 1H, J = 16.6, 7.7 Hz), 2.76 (dd, 1H, J = 13.4, 9.6 Hz), 2.49–2.43 (m, 2H); 13 C{ 1 H} NMR (CDCl 3 , 100 MHz): δ 172.6, 153.5, 136.7, 135.3, 129.4, 128.9, 127.4, 115.8, 66.2, 55.2, 37.9, 34.8, 28.2.…”