1 H NMR ( MeOD , 400 MHz ) : δ ppm 8 . 65 ( s , 1 H ) , 8 . 18 ( s , 1 H ) , 7 . 84 - 7 . 82 ( m , 3 H ) , 7 . 70 - 7 . 58 ( m , 3 H ) 6 . 92 ( t , J = 54 . 8 Hz , 1 H ) , 6 . 71 ( s , 1 H ) , 4 . 01 ( s , 3 H ) . ( ESI ) : m / z 368 . 0 [ M + H ] +.