1 H - NMR ( 400 MHz , DMSO - d 6 ) δ : 7 . 82 ( 2 H , d , J = 8 . 8 Hz ) , 7 . 69 ( 2 H , d , J = 8 . 8 Hz ) , 7 . 43 ( 4 H , d , J = 4 . 4 Hz ) , 7 . 359 ( 1 H , m ) , 7 . 23 ( 1 H , t , J = 7 . 1 Hz ) , 7 . 07 ( 1 H , d , J = 8 . 4 Hz ) , 7 . 00 ( 1 H , d , J = 8 . 4 Hz ) , 6 . 91 ( 1 H , m ) , 5 . 17 ( 2 H , s ) , 3 . 54 ( 3 H , s ) .