1H NMR (400 MHz, CDCl3) δ 6.25 (d, J= 1.5 Hz, 1H), 6.17 (d, J= 1.6 Hz, 1H), 5.83 (t, J= 1.14 Hz, 1H), 5.59 (d, J= 1.5 Hz, 1H), 4.49-4.40 (m, 1H), 4.28-4.13 (m, 4H), 2.91 (bs, 1H), 2.49-2.31 (m, 2H), 1.91-1.68 (m, 3H), 1.35-1.22 (m, 6H).
13C NMR (100 MHz, CDCl3) δ 167.3, 166.5, 142.2, 140.1, 125.1, 124.9, 70.5, 60.8, 34.9, 28.0, 14.0.