1 H - NMR ( CDCl 3 , δ , ppm ) : 3 . 49 ( 2 H , t ) , 3 . 78 ( 2 H , t ) , 4 . 40 ( 2 H , s ) , 5 . 13 ( 1 H , s ) , 7 . 37 ( 1 H , d ) , 7 . 56 ( 1 H , dd ) , 8 . 31 ( 1 H , d ) , 9 . 34 ( 1 H , brs )