1 H - NMR ( 400 MHz , CDCl 3 ) δ : 8 . 26 ( 2 H , d , J = 6 . 8 Hz ) , 7 . 82 ( 2 H , dd , J = 7 . 0 and 1 . 8 Hz ) , 7 . 65 ( 2 H , d , J = 8 . 8 Hz ) , 7 . 49 ( 2 H , dd , J = 6 . 8 and 2 . 0 Hz ) , 7 . 39 - 7 . 26 ( 5 H , m ) , 6 . 90 ( 2 H , d , J = 9 . 2 Hz ) , 6 . 80 ( 2 H , d , J = 8 . 8 Hz ) , 5 . 23 ( 2 H , s ) , 5 . 02 ( 2 H , s ) .