¹H NMR (400 MHz, CDCl₃) δ 6.88 (d, J = 7.1 Hz, 2H), 6.74 (d, J = 8.7 Hz, 1H), 5.94 (s, 2H), 5.46 (s, 1H), 5.08 (s, 1H), 3.56 – 3.45 (m, 2H), 2.65 (d, J = 4.2 Hz, 2H), 1.76 (dd, J = 20.2, 3.9 Hz, 6H). ¹³C NMR (101 MHz, CDCl₃) δ 175.80, 148.65, 147.87, 147.83, 130.66, 119.74, 109.92, 108.15, 106.29, 101.16, 51.83, 37.57, 29.98, 28.65, 23.44. HRMS (EI): calcd for C₁₅H₁₇NO₃: 259.1208, found: 259.1211。