1 H NMR ( 300 MHz , CDCl 3 ) δ : 8 . 42 ( s , 1 H ) , 8 . 18 ( s , 1 H ) , 7 . 80 - 7 . 77 ( m , 1 H ) , 7 . 65 - 7 . 62 ( m , 1 H ) , 7 . 50 ( s , 1 H ) , 5 . 74 ( br s , 1 H ) , 4 . 44 ( q , J = 6 . 0 Hz , 2 H ) , 1 . 45 ( t , J = 6 . 0 Hz , 3 H ) .