1 H NMR ( 500 MHz , DMSO - d 6 ) : δ ppm 11 . 82 ( s , 1 H ) , 10 . 65 ( s , 1 H ) , 8 . 03 ( d , J = 6 . 8 Hz , 1 H ) , 7 . 91 ( d , J = 8 . 0 Hz , 1 H ) , 7 . 85 ( d , J = 8 . 5 Hz , 1 H ) , 7 . 81 - 7 . 78 ( m , 1 H ) , 7 . 71 - 7 . 66 ( m , 2 H ) , 7 . 53 ( d , J = 2 . 5 Hz , 1 H ) , 7 . 26 ( d , J = 2 . 0 Hz , 1 H ) , 6 . 55 ( s , 1 H ) , 4 . 12 ( s , 3 H ) . ( ESI ) : m / z 385 . 9 [ M + H ] +.