1 H NMR ( 400 MHz , DMSO - d 6 ) δ 10 . 57 ( s , 1 H ) , 8 . 49 ( s , 1 H ) , 8 . 04 ( d , J = 2 . 0 Hz , 1 H ) , 7 . 63 ( d , J = 2 . 0 Hz , 1 H ) , 7 . 54 ( d , J = 8 . 4 Hz , 1 H ) , 7 . 28 ( m , 1 H ) , 7 . 06 - 7 . 13 ( m , 3 H ) , 6 . 97 - 7 . 01 ( m , 2 H ) , 6 . 67 - 6 . 69 ( m , 2 H ) , 6 . 55 - 6 . 58 ( m , 1 H ) , 6 . 41 - 6 . 43 ( m , 1 H ) , 6 . 10 ( dd , J = 2 . 0 , 2 . 0 Hz , 1 H ) .