1 H NMR ( 300 MHz , DMSO - d 6 ) δ : 11 . 39 ( br s , 1 H ) , 8 . 43 ( d , J = 7 . 9 Hz , 1 H ) , 8 . 16 ( d , J = 7 . 9 Hz , 1 H ) , 7 . 76 - 7 . 73 ( m , 2 H ) , 7 . 69 - 7 . 63 ( m , 1 H ) , 7 . 59 - 7 . 53 ( m , 2 H ) , 7 . 48 - 7 . 43 ( m , 1 H ) , 7 . 35 - 7 . 31 ( m , 1 H ) , 7 . 10 ( s , 1 H ) , 4 . 03 ( s , 3 H ) .