1 H NMR ( 400 MHz , CDCl 3 ) : δ 10 . 87 ( br . s , 1 H ) , 8 . 46 - 8 . 45 ( m , 1 H ) , 8 . 18 ( s , 1 H ) , 7 . 80 - 7 . 76 ( m , 3 H ) , 7 . 40 - 7 . 38 ( m , 2 H ) , 7 . 12 - 7 . 07 ( m , 1 H ) , 4 . 79 ( m , 2 H ) , 4 . 31 - 4 . 20 ( m , 4 H ) , 3 . 75 - 3 . 62 ( m , 2 H )