1 H NMR ( 400 MHz , CDCl 3 ) : δ 10 . 19 ( br . s , 1 H ) , 8 . 51 ( d , 1 H ) , 7 . 82 ( m , 3 H ) , 7 . 41 ( m , 2 H ) , 7 . 13 ( m , 1 H ) , 6 . 65 ( m , 1 H ) , 6 . 24 ( m , 1 H ) , 5 . 81 ( m , 1 H ) , 4 . 97 ( s , 1 H ) , 4 . 59 ( s , 1 H ) , 4 . 33 ( s , 2 H ) , 4 . 13 ( m , 1 H ) , 4 . 00 ( m , 1 H ) , 3 . 71 ( m , 1 H ) , 2 . 85 ( m , 1 H )