1 H NMR ( 400 MHz , CDCl 3 ) : δ 10 . 29 ( br . s , 1 H ) , 8 . 47 ( m , 1 H ) , 7 . 80 ( m , 3 H ) , 7 . 37 ( m , 2 H ) , 7 . 25 ( m , 1 H ) , 6 . 50 ( m , 1 H ) , 4 . 67 ( s , 2 H ) , 4 . 28 ( m , 2 H ) , 4 . 14 ( m , 2 H ) , 3 . 73 ( m , 2 H )