¹H NMR (400 MHz, CDCl₃) δ 9.18 (s, 1H), 8.94 (s, 2H), 7.51 (d, J = 7.7 Hz, 2H), 7.38 (d, J = 7.5 Hz, 2H), 2.98 (dt, J = 13.4, 6.7 Hz, 1H), 1.30 (d, J = 6.7 Hz, 6H). ¹³C NMR (101 MHz, CDCl₃) δ 157.20, 154.75, 150.06, 134.30, 131.70, 127.56, 126.94, 33.92, 23.89.