1 H NMR ( CDCl 3 , 400 MHz ) : δ ppm 9 . 72 ( s , 1 H ) , 8 . 66 ( s , 1 H ) , 8 . 23 ( d , J = 8 . 8 Hz , 1 H ) , 8 . 05 ( d , J = 8 . 4 Hz , 1 H ) , 7 . 93 ( s , 1 H ) , 7 . 85 - 7 . 83 ( m , 1 H ) , 7 . 66 - 7 . 61 ( m , 3 H ) , 6 . 69 ( t , J = 54 . 6 Hz , 1 H ) , 4 . 36 ( s , 3 H ) . ( ESI ) : m / z 402 . 9 [ M + H ] +.