1 H NMR ( CDCl 3 , 400 MHz ) δ 8 . 72 ( d , J = 3 . 4 Hz , 1 H ) , 8 . 39 ( d , J = 8 . 9 Hz , 1 H ) , 7 . 79 - 7 . 75 ( m , 1 H ) , 7 . 68 ( d , J = 7 . 7 Hz , 1 H ) , 7 . 35 - 7 . 33 ( m , 1 H ) , 6 . 49 ( d , J = 9 . 0 Hz , 1 H ) , 3 . 32 ( s , 3 H ) ;