1 H NMR ( CDCl 3 , 600 MHz ) , δ ( ppm ) : 5 . 35 ( 2 H , s ) , 7 . 16 - 7 . 19 ( 1 H , m ) , 7 . 23 - 7 . 25 ( 2 H , m ) , 7 . 49 ( 2 H , d , J = 7 . 2 Hz ) , 7 . 61 ( 2 H , d , J = 7 . 8 Hz ) , 7 . 64 - 7 . 67 ( 2 H , m ) , 8 . 00 ( 2 H , d , J = 8 . 4 Hz ) , 8 . 10 ( 1 H , dd , J = 1 . 2 , 8 . 4 Hz ) , 8 . 59 - 8 . 62 ( 2 H , m ) , 10 . 08 ( 1 H , s ) .