1 H NMR ( 400 MHz , DMSO - d 6 ) δ 10 . 62 ( s , 1 H ) , 8 . 35 ( s , 1 H ) , 8 . 23 ( d , J = 1 . 6 Hz , 1 H ) , 8 . 18 ( d , J = 7 . 2 Hz , 1 H ) , 7 . 67 - 7 . 73 ( m , 2 H ) , 7 . 52 - 7 . 57 ( m , 1 H ) , 7 . 49 ( dd , J = 2 . 0 , 8 . 8 Hz , 1 H ) , 7 . 39 - 7 . 43 ( m , 1 H ) , 5 . 92 ( dd , J = 2 . 0 , 2 . 0 Hz , 1 H ) , 5 . 86 ( m , 2 H ) , 3 . 47 ( s , 6 H ) .