1 H NMR ( 300 MHz , CDCl 3 ) δ 8 . 33 ( s , 1 H ) , 8 . 13 ( s , 1 H ) , 7 . 16 ( d , J = 8 . 1 Hz , 1 H ) , 6 . 56 - 6 . 60 ( m , 1 H ) , 6 . 43 - 6 . 49 ( m , 2 H ) , 4 . 42 ( d , J = 6 . 0 Hz , 2 H ) , 3 . 90 - 3 . 81 ( m , 12 H ) .