1H NMR (400 MHz, CDCl3) δ 7.38 (d, J = 7.7 Hz, 2H), 7.32 (d, J = 7.4 Hz, 2H), 7.24 (s, 1H), 6.11 (s, 1H), 4.31 (s, 2H), 3.92 (m, 2H), 2.51 (s, 2H). 13C NMR (100 MHz, CDCl3) δ 140.3, 134.2, 128.4, 127.3, 124.7, 122.5, 65.9, 64.5, 27.2.