“…After that, the reaction mixture was
stirred at rt for 6 h before it was diluted with ethyl acetate, washed with
brine, dried over Na 2 SO 4 and concentrated under
reduced pressure. Chromatographic purification (6% ethyl
acetate/hexanes) afforded the title compound as a colorless oil (140 mg,
89%):
[ α ] D 21 +80.5
( c 1.225, CH 2 Cl 2 ). 1 H
NMR (500 MHz, CDCl 3 ) δ 7.93 (d, J
= 1.7 Hz, 1H), 7.61 – 7.53 (m, 3H), 7.53 – 7.29 (m,
14H), 5.72 (d, J = 1.5 Hz, 1H), 5.68 (s, 1H), 5.51
(d, J = 1.3 Hz, 1H), 5.22 (s, 1H), 4.94 (d,
J = 11.8 Hz, 1H), 4.73 (d, J
= 11.9 Hz, 1H), 4.40 (m, 2H), 4.35 (td, J =
9.7, 5.1 Hz, 1H), 4.29 (t, J = 10.0 Hz, 1H), 4.28
(dd, J = 10.2, 5.0 Hz, 1H), 4.10 (dd,
J = 3.1, 1.4 Hz, 1H), 4.05 (dd,
J = 9.7, 3.1 Hz, 1H), 3.90 (t,
J = 10.1 Hz, 1H).…”