1 H NMR ( 500 MHz , DMSO - d 6 ) : δ ppm 11 . 98 ( s , 1 H ) , 10 . 11 ( s , 1 H ) , 8 . 18 ( s , 1 H ) , 8 . 16 - 8 . 11 ( m , 2 H ) , 7 . 91 ( d , J = 8 . 5 Hz , 1 H ) , 7 . 85 - 7 . 82 ( m , 1 H ) , 7 . 76 - 7 . 70 ( m , 2 H ) , 6 . 82 ( s , 1 H ) , 4 . 22 ( s , 3 H ) , 3 . 00 ( s , 3 H ) . ( ESI ) : m / z 397 . 0 [ M + H ] +.