1 H NMR ( 500 MHz , DMSO - d 6 ) : δ ppm 12 . 13 ( s , 1 H ) , 10 . 58 ( s , 1 H ) , 8 . 31 ( s , 1 H ) , 8 . 24 - 8 . 22 ( m , 1 H ) , 8 . 01 ( d , J = 8 . 5 Hz , 1 H ) , 7 . 80 ( d , J = 8 . 5 Hz , 1 H ) , 7 . 70 - 7 . 67 ( m , 2 H ) , 7 . 54 ( s , 1 H ) , 7 . 23 ( d , J = 2 . 0 Hz , 1 H ) , 7 . 13 ( d , J = 2 . 0 Hz , 1 H ) , 4 . 12 ( s , 3 H ) . ( ESI ) : m / z 385 . 9 [ M + H ] +.